Since 1981, more than 80,000 people in Britain have converted to Rome. The Catholic Church, with its declining attendances and falling birth count, needs them badly. They are often more committed and more intense about their faith than cradle Catholics, for conversion requires an intense effort, both emotional and spiritual. Many of those who met Cardinal Hume last Sunday were in tears, such was the impact of coming so close to the moment of total acceptance by the church.
Conversion nowadays usually consists of attending Rite of Christian Initiation for Adults courses, lasting six months to a year.
With fewer priests than ever (despite the recent influx of Anglican priests opposed to women's ordination) much of this work is now done by the laity. For certain people, one-to-one instruction from a priest, such as the Franciscan Father Michael Seed, is available. He guided the politicians John Gummer and Ann Widdecombe.
Why join? Paul Warren, a children's author and illustrator, was received into the church last Easter. Like Mr Blair, his wife was a Catholic and his children had been baptised as Catholics. His eldest son, like Mr Blair's, goes to the Oratory School in Fulham.
He says: "As a child of the Sixties I was pretty wild, though I also felt in some vague way that my life must have some purpose. God, perhaps? If so, how could I find Him? Needless to say I took a few short cuts in my search, and over the years I garnered a motley ragbag of mystical ideas.
"It sounds wonderful - I could mix and match. I could practically invent my own religion. But my heart wasn't in it. It just didn't feel right. My belief in God may have deepened, but I wasn't a Taoist, a Navajo or an Aztec. I felt a stranger in a strange land, never fully at home. I was still searching.
"And then an odd thing happened. One day, searching through some old family photographs, I came across my C of E baptism certificate. I had no idea - my parents had never been churchgoers - but quite unexpectedly the discovery touched me. It meant something to me, as if a seed, planted all those years ago, had suddenly bloomed. I realised I had come full circle. I had rediscovered my Christian roots."
But what could Mr Warren do about it? "My wife was Roman Catholic and our children were preparing for a Catholic education. The Church of England was going through changes that suggested too many shifting uncertainties. If I was coming home, I didn't want to arrive in the middle of a family row. On the other hand, I found that the Catholic Church was also developing; it too was re-examining its roots and the teaching of the Church fathers. It had looked at many of its medieval accretions and was seeking harmony between the Sacraments and the Word of God. I was also drawn by the Church's reverence for Mary and by the humanity of the saints. It seemed a very human church. It stirred my faith: my head and my heart."Reuse content