City yesterday signed Ferguson from Rangers for an undisclosed fee in the region of £1.2million.

The Scottish champions accepted a bid from the Barclays Premier League outfit on Wednesday as McLeish stepped up his long-standing interest in the former Scotland captain.

And the 31-year-old completed the move yesterday afternoon, signing a three-year contract to return to England for the first time since an injury-plagued spell at Blackburn which ended in 2005.

McLeish managed Ferguson during his time with Scotland and Rangers and believes the midfielder still has much to offer.

McLeish told the Rangers website, www.rangers.co.uk: "Barry has played at a very high level for Rangers, in big games.

"Maybe the Scottish league is not the strongest, certainly not anywhere near the Premier League, but he's played a good level of games, in the Champions League, the Celtic fixture and cup finals.

"I think he has got unfinished business in England.

"He started with a bad injury at Blackburn, then fought his way back to fitness, and the reports I got at that time, before he came back to Rangers, was that he was playing extremely well.

"But maybe he didn't stay long enough for people to make a full assessment of him. So I think in that respect Barry will want to come down with something to prove.

"They have barely started pre-season training but again, from the reports I've had, he's been up there in the fitness testing they have done. He's always been a pretty fit guy."

Ferguson's time at Rangers soured last season when he was stripped of the captaincy following a breach of discipline while on international duty.

He returned for the final three games of the season but his future remained in doubt. He joins compatriots McLeish, Garry O'Connor and James McFadden at St Andrews.

McLeish said on Birmingham's website, bcfc.com: "For me, Barry is a midfielder at his peak.

"I don't think 31 is too old for a central midfielder of great experience.

"Players like Gordon Strachan and Gary McAllister continued playing into their late 30s and these were guys who were not afraid of the ball.

"I think Barry can play on for a good few years yet.

"He's a guy that always turned up for work. By that I mean that his appearances over the years have always been fantastic.

"Barry has got the culture of the true-grit Brit, who will go through brick walls to play football. He has a winning mentality, and that is proven by all the winners' medals he has won."