Gary Cahill does his best to say the right thing about Martin O’Neill, but cannot resist the opportunity to express his true feelings.

It is not just his flat vowels that give away his upbringing in Sheffield, as Yorkshiremen rarely make good diplomats.

Cahill’s contention that O’Neill made a mistake in allowing him to leave Aston Villa is hardly earthshattering, but it is still unusual to hear a relatively young player questioning such an experienced manager’s judgment. The Bolton Wanderers defender is speaking from a position of strength, however, because his performances have improved dramatically since leaving Villa Park for £5 million last January, to such an extent that his late call-up to the England squad in place of Joleon Lescott this week came as no surprise.

O’Neill is not the kind of individual who admits to getting things wrong, but in his heart of hearts he would probably agree. “Martin O’Neill is a great manager, but everybody makes mistakes and he’s moved on,” Cahill said. “They’ve brought in some good centre backs now, they’re doing well.

“It was agreed that it was best for me to be playing regularly, which he couldn’t guarantee. I’ve improved a lot from my days at Villa and that’s through playing week in, week out. It’s turned out well for me and my career.”

Bolton have been the chief beneficiaries of Cahill’s impatience, but it could yet backfire on them. The 23-year-old’s rapid development as a ball-playing centre back is such that he attracted interest from Manchester United and Arsenal during the summer, and he shows the assurance of a young man who recognises his worth.

With Bolton unwilling to sell, Gary Megson persuaded him to sign a contract extension that commits him to staying at the Reebok Stadium until 2012, but Cahill does not intend to stick around for ever.

“The speculation gives you a boost and shows that my hard work has paid off,” he said. “Nothing is going to happen at this stage of the season, so it’s a matter of getting my head down for Bolton and putting in the performances that have got me here.

“I had two years left on my contract and I just extended it by a year. In the future who knows what is going to happen? If a big club comes in, I do not think there will be a problem with that, but at the moment I am enjoying my time at Bolton.”

Cahill’s next aim is to go from the standby list to becoming a regular squad member so that he can emulate his hero Des Walker by representing England at a World Cup finals. Rio Ferdinand is likely to play in only the first of the matches against Ukraine and Belarus, and, as Fabio Capello knows all about the qualities of Matthew Upson, a first cap for Cahill is not out of the question.