Tony Blair says Christians should "speak up and speak out"

Mr Blair joined Dr Williams and the former Daily Telegraph editor Charles Moore to discuss the role of religion in public life at the latest in the series of high-profile Westminster Faith Debates in London.

He told how while in power he often disagreed with Christian groups, including on issues such as introducing supercasinos, but insisted that it was important that their views were heard.

He said that there was “something basic and fundamental” about the contribution the Church had made in Britain adding: “It is very important that that voice is heard.

Using the word “we” when referring to Christians, he added: “It is important that we are prepared to speak up and speak out from the position of faith and say we are not afraid to say this is what we believe and why we believe it.”

Laughing about Mr Campbell’s “famous instruction” to steer clear of religion, he told how while he was leader of the opposition to members of the Salvation Army had come to see him.

“At the meeting one said ‘right we are all going to kneel in prayer’," said Mr Blair.

“There were two people in my office, who shall remain nameless, who looked absolutely aghast but I said ‘you are going to have to get on your knees’.

“They said ‘for God’s sake’ and I said ‘exactly’.”

He added that it had been refreshing to meet people who were “not ashamed” of their faith.

Asked by whether the same had applied in relation to Mr Bush he suggested he would have prayed with the former US president had he been asked to.

“It would not have been wrong – it’s just that it didn’t happen,” he said.

There was applause for De Williams when, in answer to a question from the floor, he told had voted in the Lords against Mr Blair’s plans to liberalise gambling laws.

“I did think the idea that you could regenerate an impoverished area of Manchester by importing a supercasino seemed to me utterly, utterly bizarre.”

Dr Williams also addressed the series of controversies about Christianity in public – such as the wearing of crosses – adding: “I’m just a little wary about jumping too quickly in to the victim posture.”