He returned to St James's Park at the turn of the year after Preston said they did not want to take up the option of another six months.
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Allardyce threw Carroll back in at the deep end in the last round of the FA Cup against Stoke City, and the youngster almost won the tie with a last-gasp chance.
Since then, Allardyce has been replaced by Kevin Keegan, but Carroll has been involved in the first-team squad with Oba Martins away on international duty.
Carroll: "It's great to be back here.
"The Stoke game was the first one after I came back from Preston. I didn't expect to be involved but I came on, which was a bonus.
"I'm just happy to be back and in the picture.
"I was very young (the last time Keegan was here). But I remember the players he had all those years ago, it was a fantastic team.
"Hopefully he can put this team together and help us get back to the top of the League.
"I haven't spoken to the new manager one-to-one yet.
"But I am looking forward to seeing what he says.
"If I score in the reserves while there are injuries in the first team, I will keep getting closer to the first-team picture.
"But I won't take anything for granted.
"I was delighted to get a hat-trick at Middlesbrough, but I was just doing what strikers do.
"It's important to get goals, and with the new manager coming it's great for me."