However, the 70-year-old is confident that he would have led the club back to the Premier League if they had kept faith with him, blaming the team's form so far this season on injuries and a lack of transfer activity.
"I am disappointed. It's been difficult, I have had one week with a new team and new players, one week. It's not an excuse but today I had three of the forwards missing who I would have picked, probably the three most exciting players in all honesty. It takes time to build a football team, not one week. I didn't get the players in I was after in pre-season and suddenly I have got a load of players in," he told the Birmingham Mail.
"A lot of the targets I was after I couldn't get over the line. And I still felt that given time I would have given them a team that would have been challenging for promotion, I had no doubt about that. Maybe not this year but over the next two years I would have got promotion.
"I had to do well this year but I would have stayed because I loved it there, absolutely loved my time there. I am not an idiot, I am not a silly person who goes around saying things, I think I have been around long enough."
Birmingham have lost seven of their 10 games across all competitions this season, including each of their last six.