However, a couple of late penalties from Owen Farrell secured the win.
Read how all the action unfolded below.
Good afternoon! Stuart Lancaster's England side will continue their preparations for the Rugby World Cup in around an hour when they take on Ireland at Twickenham. Let's start with a reminder of the starting lineups for this afternoon's clash.
ENGLAND STARTING XV: Brown, Watson, Joseph, Barritt, May, Ford, B Youngs, Marler, T Youngs, Cole, Lawes, Parling, Wood, Robshaw, Morgan
IRELAND STARING XV: Zebo, Bowe, Payne, Henshaw, Kearney, Sexton, Murray, McGrath, Best, Ross, Toner, O'Connell, O'Mahoney, O'Briwn, Heaslip
The home side have made five changes to the lineup that starting the 25-20 defeat to France last time out. Brad Barritt, Anthony Watson, Geoff Parling, Tom Wood and Ben Morgan are all included. Luther Burrell, Jack Nowell, Joe Launcbury, James Haskell and Billy Vunipola are the players making way.
For the visitors, Joe Schmidt has named almost an identical team to the one that sealed the Six Nations title earlier this year. Simon Zebo starts at full-back ahead of Rob Kearney, while Dave Kearney and Jack McGrath come in for Luke Fitzgerald and Cian Healy, who is still recovering from neck surgery. Tadhg Furlong, who made his debut against Wales last time out, is among the replacements.
It's less than two weeks until England begin their World Cup campaign. The host nation are in a tricky group with Wales, Australia Uruguay and Fiji, who will be their first opponents at Twickenham on September 18.
Ireland's first fixture is the following day at the Millennium Stadium in Cardiff, where they will take on Canada. Joe Schmidt's side will also face France, Italy and Romania in Pool D.
The home side received quite a welcome when they arrived at the stadium a short time ago:
Ahead of this match, England's forwards coach Graham Rowntree has insisted that the side can challenge for the trophy at the World Cup: ""This team is going to get better and better as it gets more experienced but I promise you this team can win a World Cup now. Ireland are one of our fiercest rivals, with some true warriors. It's going to be a real test for us, that's why I say our World Cup starts on Saturday. But we're at Twickenham and we've got our home support. We're spoiled really, the support we're getting now is unbelievable. It makes the hairs on my neck stand up just thinking about that roar when the guys run out."
Joe Schmidt wasn't happy with his side after they lost to Wales last time out, and Paul O'Connell believes that a few harsh words from the coach will have had an effect: "Joe talks hard to us, but one thing we have is that we're actually quite good at this stage of almost troubleshooting things ourselves. You come off the pitch, watch the game once and know straight away there are a few things we slipped on and the players will be able to address them themsevles. Joe is tough on it and while those meetings are tough, I think guys enjoy them and get a lot out of them."
Both sides will be hoping that their preparations for this year's tournament help them improve on their 2011 performances. Both teams won their group in the tournament in New Zealand four years ago, but Ireland lost to Wales in the quarter-finals, while England were knocked out by France.
The last meeting between these two sides came in the Six Nations back in Marsh. On that occasion, it was Ireland who secured the win, beating England 19-9, but that match was in Dublin. It will be a different prospect for the Irish side at Twickenham, having lost on their last visit to the ground in 2014.
With around half an hour until the match gets underway, both captains have led their side out onto the pitch for their final warmups in the last couple of minutes. The stadium is still filling up, but there's a huge cheer for the home side.
Former England fly-half Jonny Wilkinson is among those watching today:
England forward Tom Wood admits that playing at Twickenham is always special: ""It is a pretty incredible feeling turning up at Twickenham. That is my moment. That is when you look up at the tiers of the stand and really reflect on what you have achieved, how exciting it is to be there but also what a responsibility you have."
Meanwhile, Ireland scrum coach Greg Feek told BBC Sport that the visitors need to get the basics right today: ""In a match such as this, everyone wants to win. But it's important to remember there's a bigger thing coming. For us, it's about getting the basics right, especially around the breakdowns and set-pieces. That will give us confidence going into the World Cup."
There's a chance that these two sides could meet again in the semi-finals of the World Cup if they come through their groups. The winner of Pool A, which features England, and the runners-up in Ireland's Pool D will go into the same half of the draw, and vise-versa. If they both win their groups, then they won't play again until the final, if they both get that far.
The teams have just made their way back in following their warmups. The anthems will take place before kickoff, so the two sides should be heading back out ready for kickoff in the next 10 minutes.
Giving a final interview before his side come out in front of the Twickenham crowd, Stuart Lancaster tells BBC Radio 5 live: "It's crucial for both teams to win. It doesn't feel like a warm-up; it feels like a test match, with two quality teams going at full strength. It's about getting the detail right, the big moments in games. To win the World Cup, you've got top hit the top percentage for seven games in a row."
The flags of both countries are being displayed on the playing surface as 'Swing Low Sweet Chariot' fills the stadium. The teams are starting to assemble in the tunnel ready to head back out for kickoff.
The players run out to a huge cheer from the Twickenham crowd, led by Chris Robshaw and Paul O'Connell. The Irish anthem will be the first to be performed. Although it's the English fans that dominate the crowd this afternoon, there are still plenty of Irish fans that have made their way across the Irish Sea to cheer on their side.
'God Save The Queen' following, much to the delight of the home crowd. With the pre-match formalities over, the players line up ready to get the match underway. Incidentally, Welshman Nigel Owens in the referee in charge this afternoon.
KICKOFF! George Ford gets the action underway.
England are piling on the pressure early on, with Mike Brown trying to slip down the sideline, only to have his run halted by Tommy Bowe. The home side work the ball across the pitch towards Jonathan Joseph, but Ireland are doing just enough to keep the hosts out for now.
TRY! England 5-0 Ireland (Jonny May)
Ben Youngs gets the ball out wide on the left to Jonny May. Simon Zebo tries to get the tackle in, but the full-back is shoved away by May, leaving him to leap over in the corner.
CONVERSION! England 7-0 Ireland (George Ford)
George Ford has his first site at the posts, and easily kicks it through for the extra two points from out wide. What a start for the hosts.
PENALTY! England 7-3 Ireland (Johnny Sexton)
It doesn't take Ireland long to get off the mark as Jonny May is penalised for taking a man out in the air, giving Johnny Sexton his first attempt of the afternoon. It's a long way out, but the experienced fly-half curls it round superbly to cut England's lead.
There's a delay as referee Romain Poite, who is one of Nigel Owens' assistants this afternoon, appears to have picked up an ankle injury and is getting treatment. He's soon back up though, and England have a lineout near the half-way line.
Tom Youngs fires the ball in from the lineout to brother Ben, but they're unable to create anything from it, so it's kicked back to Dave Kearney. Joe Marler gets it back still in Ireland territory. May manages to break down the left again, but this time Zebo is ready for him and pounces on the ball as the try-scorer kicks it forward.
TRY! England 12-3 Ireland (Anthony Watson)
George Ford gets the ball in space, and kicks it across to Anthony Watson. He's being marked by Zebo, who goes up to try to stop the ball finding the Bath man, but Watson muscles him out of the way, before stretching to take it across the line.
MISSED CONVERSION! If anything, George Ford has an easier kick than he did after the first try, but this time it goes wide.
England have the ball back again, and try to head deeper into Ireland territory, but Conor Murray is left floored by a heavy tackle, and has to go off. He looks rather shaken up, having taken a couple of minutes before being able to sit up.
Barrett passes the ball across to Brown, who in turn finds Joseph, but Ireland have numbers behind the ball to halt his charge. It doesn't take England long to regroup, with Robshaw trying to find a gap to go through under the posts, but a knock-on gives the visitors the scrum.
Ireland have the ball inside the England 22 for the first two today, with Best and O'Connell looking to get the visitors back into the match, but the latter's kick forward ends up in the hands of Brown, before it's booted clear for a lineout on the half-way line.
TRY! England 17-3 Ireland (Jonny May)
Nigel Owens awards the try on the field as Jonny May leaps over for his second of the day, but the TMO is in the referee's ear, so they're going to take a look at Ben Youngs's pass to the scorer, which looked a little forward.
NO TRY! What a disappointment for England! George Ford was about to take the conversion kick when Owens called for the replay, but the footage clearly shows that Youngs' pass was forward. It had been an excellent finish from May, who hurdles a couple of Ireland players to avoid tackles and sneak over in the corner.
Having been let off the hook after seemingly having let England add a third try, Ireland are trying to build some possession and territory to get back in this match. Johnny Sexton and Paul O'Connell move the ball through the middle, but Sexton's pass towards Best misses its target.
England have a scrum, but Ireland manage to win it back, with Tommy Bowe driving towards the England try line, but Mike Brown is there to force the turnover and kick it clear. England haven't had too much to do at the back so far, but Brown has been excellent when called upon so far.
Kearney tries to work the ball down the left, making up a decent chunk of ground before being brought down by Barrett, but Joseph gives away the penalty. Sexton kicks it out for a lineout just short of the try line, but Parling steals it for England. He has been excellent in set pieces for England in the warm-ups.
May has the ball in England territory, and kick it forward to himself. He survives a heavy challenge from Best to get it across to Anthony Watson, who sprints forward looking for his second try of the afternoon, being brought down just short by Zebo.
Ben Morgan looks sharp as he tries to weave through the Ireland line, eventually being brought down. He keeps possession and gets it back to Ben Youngs, who boots it back for a lineout just short of the tryline. England try to hurry the visitors as the ball is delivered back in, but Best takes it for Ireland.
England have a lineout of their own straight away, with Parling claiming it before May looks to make progress down the left, where he has found so much space already in this match, but he's closed down this time.
Ireland have a scrum right on the stroke of half time, from which Heaslip manages to get it away to Kearney. Best powers through the middle, sensing a chance to get a try on the board for the visitors just before the break, with Sexton and Toner also getting involved, but Joseph and Watson get across to close the gap.
Sean O'Brien has a last-gasp chance, but is brought down while stretching for the line, allowing England to maintain their 11-point lead at the break.
HALF TIME: England 12-3 Ireland
So at the break, tries from Jonny May and Anthony Watson put England ahead, while Ireland have just three points on the board courtesy of a Johnny Sexton penalty.
Jonny May will certainly be happy with his performance so far. He's been almost untouchable down the left, only being denied a second try because of a forward pass in the build up. Assuming he stays on in the second half, it wouldn't be a surprise to see him adding another.
Ireland haven't had much of the ball in England's half, but mistakes at the back have cost them too. Simon Zebo missed a tackle to stop the first try, while losing out to Watson in the air for the second. Tommy Bowe and Jamie Heaslip have looked rather laboured too so far. Joe Schmidt will be hoping to see a better performance from his men after the break.
The players are starting to make their way back out ready for the second half.
RESTART! Johnny Sexton gets the action back underway.
Ireland have seen the majority of the possession since the restart, but they haven't created anything to stretch England so far. However, there is an injury concern as Simon Zebo calls the trainer on, resulting in Mike Brown putting the ball out to allow his opposite number to head off.
Ireland have a lineout, but Eoin Reddan drops the ball as he tries to bring it down, giving England a scrum. Youngs gets the ball out at the back, but Ireland are penalised for having a player stand up during the scrum, so it's a penalty for England.
PENALTY! England 15-3 Ireland (George Ford)
Ford lines up the kick, which is a long way out. It's an accurate attempt, but looks like it could be coming up a little short. However, it hits the crossbar before landing behind the posts, giving the home side three more points.
Ireland had shown promise at the start of this second half, but find themselves further behind following the penalty. Kearney and Jared Payne quickly make their way into England territory, leaving the visitors stretched at the back, forcing Barrett to give away the penalty. That's the kind of tempo Ireland need to play at if they want to overhaul England's lead.
PENALTY! England 15-6 Ireland (Johnny Sexton)
It's a simple penalty for Sexton, who just chips the ball over, starting almost in line with the posts to reduce the gap to nine points again.
TRY! England 15-11 Ireland (Paul O'Connell)
Jonny May has to put the ball into touch while under pressure as Ireland kick the ball forward, giving the visitors a lineout in a strong position. O'Connell gets it from the set piece, dragging Courtney Lawes over the line with him as he stretches the ball over.
CONVERSION! England 15-13 Ireland (Johnny Sexton)
Sexton adds the extra points, leaving Ireland just two points behind their opponents now. What a fantastic effort the Six Nations champions have put in over the last five minutes, getting them right back in this match.
Mako Vunipola is among a number of players to come off the bench for England as Lancaster rings the changes. He immediately gets involved, working with Brown to try to find a third try for the home side but their path is blocked. Launchbury tries to keep the move alive, but O'Connell is back to make the block.
Kearney and Brown both go up for a high ball, and it's the England man who comes away with it in his hands, allowing Billy Vunipola and Watson to continue to pressure for the hosts, but Payne and O'Connell force the turn over. Zebo and Sexton sprint away, but there was a knock-on, so Nigel Owens calls it back.
Here's the scorer of England's second try, Anthony Watson, in action in the first half:
© Getty Images
© Getty Images
Owen Farrell and Sam Burgess, who are also fresh off the bench, team up to keep the pressure on Ireland. The introduction of fresh legs has given England something a little extra since Ireland cut the lead to two points, but Burgess is tackled short of the try line.
Ireland have a scrum inside their own 22, which Reddan tosses back to Sexton. The fly-half kicks it away, but a touch of cramp strikes just at the wrong time, leaving him in some discomfort, and resulting in the ball being sliced short.
England try to make the most of their strong position following Sexton's slip, with Wigglesworth picking out Burgess, who is clearly keen to make an impact. Ireland win another scrum though, resulting in Sexton being asked to kick again, and he gets a better contact this time, but is still clearly troubled by cramp.
Johnny Sexton hobbles off, resulting in Ian Madigan taking over at fly-half. Ireland fans will be concerned to see the fly-half struggling so close to the World Cup, but it really did look like nothing more than cramp, so it's probably a precautionary move from Joe Schmidt.
England are on the attack again, with Robshaw and Burgess passing the ball around, before Launchbury tries to find a way through. Zebo now seems to be struggling with cramp as well, giving England an extra incentive to try to put the full-back under pressure.
Billy Vunipola skips around a couple of Irish shirts before being blocked just short of the line. He gets it away to the right, where Mike Brown is bearing down on the try line, but Ireland still have men back.
NO TRY! Richard Wigglesworth thinks that he's gone over in the corner. However, the TMO shows that the ball came down short, and that there was an offside in the buildup, with Robshaw handing the ball off to Tom Wood, who was stood ahead of him, so it's rightly chalked off.
England are trying to get back into a try-scoring position, with a long kick forward dropping to May, but Reddan is in the right place to beat him to it.
PENALTY! England 18-13 Ireland (Owen Farrell)
England force the penalty from a rolling maul as a result of a lineout. Farrell hasn't had a shot at the posts yet this afternoon, but his first attempt it good, as he extends England's lead to five.
England just need to keep possession and prevent Ireland getting another chance in the final five minutes, which Tom Wood tries to do, carrying the ball back into Ireland territory.
Lawes gives away a scrum for a knock on, but the visitors can't keep hold of the ball, allowing England to force another penalty. If this goes over, England will surely seal the win. Farrell lines it up...
PENALTY! England 21-13 Ireland (Owen Farrell)
It's tight, but Farrell just squeezes it inside the left upright, extending the home side's lead to eight points. That's surely enough for Lancaster's side to take the win. Ireland look like they're on the hunt for a late consolation though.
Kearney and Maddigan pile forward, but Sam Burgess wins it back for England. May kicks it forward as England break with a counter, but he can't get on the end of his won kick.
FULL TIME: England 21-13 Ireland
Ireland certainly improved after a sloppy first half, but England did just enough to hold on for the win, with a couple of late kicks from Owen Farrell putting the win beyond doubt.
That's all from this match, but stick around as we'll be bringing you live coverage of the warm-up match between Wales and Italy in a few minutes. Until then, thanks for joining me this afternoon. Goodbye.