Father Seed is a Franciscan friar with 20th-century tastes - horror films, pizza - who takes confession and says mass at the Houses of Parliament as their unofficial Roman Catholic chaplain. He is also "priest of choice" to those in the worlds of politics and high society who want to make the move into the Catholic Church that has become highly fashionable in recent years.
So when it emerged last week that the historian, former defence minister and self-confessed adulterer Alan Clark was thinking of embracing Catholicism, few Westminster insiders were surprised to hear that it was Father Seed who had quietly been instructing him in the faith. He had already helped Mr Clark's fellow Tories Ann Widdecombe, the Employment minister, and John Gummer, Secretary of State for the Environment, go across from the Church of England, whose decision to ordain women as priests had so disappointed them.
A northerner who keeps a copy of The Wit and Wisdom of Mae West (another celebrated convert) on the desk of his office at Westminster Cathedral, Father Seed has described himself to friends as "not a spiritually content person". He is "still on a journey". Above the desk is a quotation from another of his heroes, Mahatma Gandhi: "I love Jesus Christ, but I cannot stand Christians because they are so unlike Jesus Christ."
A young-looking 37, Father Seed is a naturally funny man who has described himself as never formal. Those he counsels are received over tea or coffee in the office, or in his small and disorganised bedroom in a friary behind the cathedral.
He is one of 10 priests at the cathedral who offer instruction. But he does not talk just to politicians. The Duchess of Kent learnt from him before she was received into the Church in January 1994. At Parliament he isas likely to be found talking to the cooks, cleaners or other staff as the politicians. As Cardinal Hume's ecumenical adviser, he also has to deal with priests from other churches. In the case of Anglican clergy, that increasingly means helping them to convert.
But you will not hear Father Seed gloat about this growing tide. He turns down media requests to talk about his work, because of "the deeply personal nature of discussions between a priest and those who are seeking to develop their spiritual life" and because he is unhappy about drawing attention to himself and appearing to denigrate other Christian traditions he respects. While greeting the conversion of Ann Widdecombe in 1993 as "an authentic movement of the Holy Spirit", he told the congregation at her first communion that there must be "no hint of triumphalism".
Perhaps that is because Michael Seed was a convert himself, with a background in several other kinds of Christianity. He was an adopted child, with a turbulent childhood: "My mother killed herself on a railway track just outside our house when I was seven," he has said. "I had to cross that track every day to get to school. The other children used to insult me."
His adoptive father and grandfather were also dead within two years, so he was raised by his elderly grandmother, a staunch member of the Salvation Army. He had what would now be called learning difficulties: he could not read or write properly until he was 12, went to a special boarding school, and still describes himself as dyslexic. He became a member of the Strict and Particular Baptist Church, which taught that both Catholicism and alcohol were ungodly. But it was the smell of incense and drink that caused him to convert, at the age of 17.
"One evening I went into a Catholic church which was next to a pub," he has said. "Half the congregation was saying the rosary, the priest had his back to them, it was totally in Latin: absolutely dull and boring and dreadful, but absolutely packed. All I could smell was incense and alcohol. I had a kind of conversion experience. It was a church of sinners to me, because at that time alcohol was a sin and I wasn't allowed to do anything, even go to the cinema."
He had left school withoutqualifications, and was fired from a job in a motorway cafe for breaking plates and putting an electric kettle in the oven (as an institutionalised child he had never made tea before). He was also sacked from a clothes shop for telling customers they could dress more cheaply elsewhere. After a string of other jobs he became a priest, and joined the Franciscan Friars of the Atonement, an order formed in 1898 to work for church unity. Many of the friars work as ecumenical officers in the US, where the order is strongest and where he gained a doctorate in theology.
Father Seed has now been at Westminster Cathedral for more than 10 years. When not seeing would-be converts, he has proved an energetic campaigner: in 1991 he raised pounds 10,000 for a project to help the homeless by compiling a book in which famous people including Lord Wilson and Bono of U2 described their ideas of Heaven. He has been one of the driving forces behind the Great Banquet, an ecumenical project by London churches in which people from widely different backgrounds will meet to eat and talk next weekend. Businessmen will sit down with bishops and homeless people with politicians including Tony Blair for the main event at Banqueting House.
Honest about his own doubts, Father Seed does not ask those he is instructing to accept all the difficult tenets of the Catholic Church, including papal infallibility and praying for the dead - many of which he still struggles with himself. But they are asked to make a commitment to try to understand over time, to accept that once you believe in the resurrection, anything is possible.
St Peter, from whom the popes trace their authority, had "a tendency to run into the darkness and make wrong moves", said Father Seed at the mass he took for Ann Widdecombe. Jesus, he added, seemed to "specialise in choosing very weak and awkward people". In a Christmas message for the Independent soon afterwards, he described Christians as "sometimes odd, cranky and slightly weird".
Once he has got to know those who come to him, he asks them to write down the pros and cons of becoming a Roman Catholic, and the arguments for and against leaving the Church they are already in. Both sides must balance, they are told. A plain speaker, he is averse to those who only want to "shit on their old Church", insisting that they rediscover what was good about it before they move on.
Ann Widdecombe describes him as an "active recruiter". "He is regarded with a lot of respect within Parliament, particularly by the Catholics," she said. "Because he came from an Evangelical background, he has a greater understanding of where converts are coming from.
"He is very much prepared to tailor what he does to the circumstances of the individual. In my case there was a lot of doctrinal discussion at hours that fitted with Parliamentary life. It was very informal. He is prepared to have everything challenged. He doesn't say, 'Why are you challenging that?' "
Father Seed accepts that Catholicism is fashionable again among intellectuals of his own generation, such as Charles Moore, editor of the Sunday Telegraph, and believes that this is because it offers some certainty and order coupled with a tolerance of doubt. Friends say it both amuses and worries him that many end up much more traditionalist, right-wing and conservative than he is, with a taste for Latin masses. "They're attracted to some form of discipline and they want answers," he has said. "It answers the mood of society at the present time."