"I am pleased with the signing. He is a player we have looked at for a while and he will make a big difference for us," Zola told the Watford Observer.
"We know his qualities and we are sure his qualities can help us. Now let's see how he does.
"We always said that Nathaniel left a big hole. Iriney [Santos] did a good job in certain types of games and Josh [McEachran] made a good impression in another types of games. We think that George can play that position in any type of game."
Thorne will remain at Vicarage Road until January.