At the end of a specially arranged meeting with the Archbishop of Siena, in the sacristy of San Gimignano's Duomo, the Prime Minister - an Anglo- Catholic - expressed how close he felt to the Catholic faith, it is claimed.
Details of his private conversation with Mgr Gaetano Bonicelli, combined with reports that he was "so familiar" with the liturgy and responses during Mass in Italy that he "hardly needed" his Missal, have prompted speculation about his keenness to convert.
It is unclear whether he received communion at the Mass but, if he did, it would not have been the first time. On previous occasions, he has taken communion in Catholic churches. Mr Blair only desisted after it came to people's notice. Earlier this year he was seen going to Sunday Mass at Westminster Cathedral without the other members of his immediate family, all of whom are Catholic.
In an interview with The Catholic Herald newspaper this week, Archbishop Bonicelli said that Mr Blair had told him "that he felt very close to the Catholic Church, and to the world of Catholicism", as they were leaving San Gimignano's main church.
However, Downing Street was extremely defensive and moved to quash the story yesterday. William Odie, the former Anglican clergyman who was recently appointed editor of The Catholic Herald, said: "I'm not quite sure why Mr Blair is so cagey about it. What's so terrible about going to talk to an archbishop? It's almost as if it's some secret vice."
Mr Odie doubted that the Prime Minister would convert because, like many Anglo-Catholics, he probably already regards himself as a Catholic. "Having been an Anglo-Catholic myself," he said, "I know very well that Anglo- Catholics feel very close to Catholicism. Quite often this is a way of having a broadly Catholic view without having to go the whole way in various beliefs."
Archbishop Bonicelli said that he found it "normal" that Mr Blair showed such an interest in Catholicism. "His wife is Catholic and so are his children. I do not find the Anglican church and the Catholic church to be very different anyway, especially in creed." He added that the Prime Minister's comments did not amount to "an affirmation of a desire to convert".
Mr Blair and his wife, Cherie, arranged the meeting with the Archbishop in San Gimignano after the couple decided to change their plans and not go to Siena. The Archbishop is understood to have offered to go to the Renaissance villa of Prince Girolamo Strozzi, where the Blairs were staying. However, since the Archbishop was planning to be near San Gimignano for a religious procession, they agreed to meet in the town.
A Downing Street spokesman denied that the conversation between the two men on 13 August ever turned to conversion. He also refused to confirm or deny whether Mr Blair received communion at Catholic services in Italy.