I see myself as a headmaster and a headmistress,” Patrick Tobin says. Not many people can say that. As principal of Stewart’s Melville College (for boys) and of Mary Erskine School (for girls) in Edinburgh, Mr Tobin does indeed combine both roles, as well as being head of the largest independent school community in Britain. He spends half the week in one school, half in the other.

At least, that is what happens in normal times. But since January Mr Tobin has also been chairman of the Headmasters’ and Headmistresses’ Conference (HMC), the body that represents the country’s 240 leading public schools. He has therefore spent a lot of time away from Edinburgh and was this week chairing its annual gathering in Jersey.

His deputy heads manage the schools while he’s away (“I’m not there half the time anyway,” he points out). But he has managed to appoint all staff and to attend a fair number of assemblies and parents’ meetings in the past nine months. Whenever he gets back to Edinburgh, he says cheerfully, there is “a great distillation of nastiness waiting for him” - all the bits nobody has wanted to touch. But he has no doubt that being HMC chairman, time-consuming though it is, is a great honour and a unique opportunity.

Much of his time has been spent on the Millennium working party - not an excuse for a dome to rise on the playing-fields of Eton but an opportunity for HMC to draw up a development plan for the next century, on which members were due to vote this week. He has also been busy helping individual member schools with their problems and responding to Government policy and initiatives. He caused a stir by remarking that citizenship education reminded him of Napoleon and Stalin and he has serious concerns about the Government’s sixth-form plans too.

Mr Tobin is a bit of an oddity, both at Stewarts’ Melville and within HMC. An English Catholic, he is head of a strictly non-denominational Scottish school. (When he was appointed in 1989, there were mutterings about an exodus of outraged staff but none left.) He is also only the second head of a Scottish school to hold the post of HMC chairman in its 128-year history.

Friendly and chatty, Mr Tobin has none of the eccentricity or booming gravitas sometimes associated with public-school heads. One fellow head described him as “a power-house of ideas”, another - rather wistfully - as “the new, professional face of the HMC rather than the old-style grandee”. He has certainly worked hard to make teachers in member schools more professional: during his three years as chairman of the HMC’s professional development committee, he gave a great boost to staff appraisal and he has also co-directed its preliminary training course for new heads.

“When I first introduced staff appraisal at Stewart’s Melville,” he says with amazement, “there were some teachers who had been there for 30 years and had never once taught in front of another teacher.”

But those who fear he may favour the professional at the expense of the truly educational, let alone the spiritual, should have had their minds set at rest by this week’s conference. Mr Tobin chose “Educating into Goodness” as its theme and asked his old schoolfriend Chris Patten to give the keynote speech on “Education, Values and Tomorrow’s World”. The theme was partly chosen in memory of their headmaster at St Benedict’s, Ealing, who was, he says, “a good man”.

The son of a scientific civil servant and a teacher, Patrick Tobin studied at Oxford before embarking, somewhat lackadaisically, on a teaching career, when one of his old teachers at St Benedict’s approached him to become head of economics at the school. He had studied history, not economics, but he managed; the PGCE came later.

He married Margery, a modern languages teacher, and moved to Christ’s College, Brecon, where he ran the rugby first XV (“as close to a religious experience as I am likely to get”). Then he became head of history at Tonbridge, which he considers his “benchmark - it’s such a wonderful school” and spent a year on an exchange at King’s, Parramatta, the oldest school in Australia.

While he was there, his aunt wrote to tell him that Prior Park, Bath, the Roman Catholic boys’ boarding school in Bath, was looking for its first ever lay headmaster. Mr Tobin got the job and then faced the formidable task of pulling the school out of decline. He enlisted the help of old boys and the local bishop; he recruited Chris Patten, then the local MP, to the governing body; he opened the doors to girls. Above all, he followed the advice of a millionaire old boy who told him: “Never plan for failure.” And it worked: when he joined the school in 1981, there were 230 pupils; now there are more than 500.

He moved up to Edinburgh in 1989, with the result that two of his four children were educated at English schools and two in the Scottish system. His eldest daughter has just started teaching French and Italian in London, while the youngest is in the sixth form at Mary Erskine.

It is often said that chairmen of HMC come from the biggest schools and there are no bigger school communities than the one Patrick Tobin now runs. But one of his strengths as HMC chairman is that he has experience of both struggling and flourishing schools. “I can say to members: ‘Very few of you have run a school as small or as vulnerable as Prior Park was in the 1980s’.”