Read Ruth Gledhill's blog on Blair's conversion

The Roman Catholic priest who was instrumental in guiding Tony Blair on his path to Rome compared the former Prime Minister last night to St Paul.

Canon Timothy Russ, parish priest at Great Missenden, the nearest Catholic church to the prime ministerial country residence at Chequers, called on Catholics who resented Mr Blair because of his voting record on abortion and stem cell research to remember the example of the Christian Church’s greatest Apostle, St Paul, a key figure in spreading the message of Christianity.

St Paul was ruthless in his persecution of early Christians before his dramatic conversion on the Road to Damascus.

“Quite a lot of people will be quite antiTony Blair at first,” Canon Russ said. “They will be unhappy that he has become a Catholic so easily. But they have to realise that St Paul had been a frightful antiChristian before he became a convert and did great things for the Church. I would advise people who are critical to wait and see what sort of man this will be, and how he might help our cause.”

On Iraq, Canon Russ – who was in discussion with Mr Blair for several years about his becoming a Catholic and is still in touch with the Blair family – said that there was no case for him to answer in terms of Catholic doctrine, because the former Prime Minister had done what he believed to be his duty.

Catholic leaders were yesterday playing down the significance of Mr Blair’s conversion. Insiders at the office of the Archbishop of Westminster, Cardinal Cormac Murphy-O’Con-nor, emphasised that the former Prime Minister is “just one more individual”. Catholic leaders were also working behind the scenes last night to dispel misunderstandings about the nature of conversion.

In Britain’s increasingly secular society, there is widespread misunderstanding about the doctrine of Christian reconciliation, or repentance, confession and forgiveness. “What Tony Blair did any time before he became a Catholic, is basically not relevant,” one insider said. “The whole point about the profession of faith is that he is professing to believe it from now.”

The Times reported exclusively this year that the number of Catholics attending Mass was on course to overtake churchgoing Anglicans in Britain for the first time since the Reformation. Figures to be published by Christian Research next year show that, only three years after an influx of immigrants from largely Catholic states joining the EU, there are now more practising Catholics than Anglicans.

Lord St John of Fawsley, the Catholic peer and constitutional expert, said that there was no constitutional significance to Tony Blair’s conversion. The Act of Settlement of 1701, which forbids the monarch or his or her heirs from marrying a Catholic if they want to retain their right to the throne, does not affect the Prime Minister’s office.

Political sensitivities made it difficult, however, for Mr Blair to contemplate converting while in office.

Lord St John said that one factor that would have inhibited Mr Blair from converting while at Downing Street was the potential destabilising effect on Northern Ireland: “He has done so much more than any other Prime Minister to bring about peace, he did not want to jeopardise that.”

Mr Blair has been criticised for not taking a sufficiently “Catholic” line in votes in Parliament on abortion and stem cell research. But Lord St John said that, apart from Mr Blair not having been Catholic while Prime Minister, the issues were not clear in any case. “I shall vote against stem cell research because I do not like the idea of cloning embryos,” he said.

He added: “On abortion, it is still possible to be a Catholic and to be in favour of abortion. St Thomas Aqui-nas [the 13th-century Dominican scholar who “proved” the existence of God] believed that abortion was legitimate until 40 days after conception.” He said the Catholic view today was that abortion was wrong, but that until relatively recently even Catholic MPs were not uniformly against abortion.