Sound the bugles, raise the flags: one of the most unusual headships in the business is about to change hands. In the summer of 2004, Nicholas Ward bows out after nine years at the helm of the Royal Hospital school, a mixed boarding school in Holbrook, Suffolk.

He is leaving because “heads should not go on too long - their sacred cows get BSE”. He says: “Schools must move forward. I’ve spent almost 30 years in boarding education and my time’s up. It’s a life you eat, sleep, breathe; it doesn’t stop at 6pm. I’m happy with what I’ve done. It’s time for someone else to take a turn.”

The job (which comes with a nine-bedroomed house) is advertised this month in The TES, although the restrained style favoured by its parent charity may not quite express its offbeat character. Here, the deep-rutted parallel cultures of state and private education merge. It may seem novel for a TV production company to sponsor an inner-city child through a top Catholic boarding school, but at RHS it is routine to confront a wide social mix of children with boarding, chapel services and a marching band.

The reason is Greenwich Hospital, a seafarers’ charity set up in 1694 by Queen Anne and funded by such diverse sources as the rent on the Royal Naval College and the confiscated booty of the 17th-century pirate Captain Kidd. Its original school buildings in Greenwich, south London, now house the National Maritime Museum, which runs an exhibition of photographs from the 19th and early 20th century, showing villainous-looking schoolboys who look as if they would marlinspike their grannies for a tot of rum.

The school gave up its London address in the 1930s, after shipping tycoon Gifford Sherman Reade left a small fortune to the charity, enabling a move to new, purpose-built facilities at Holbrook on the river Stour, with 11 handsome boarding houses, an immense clock tower (up which the current chaplain plays the bagpipes), a parade ground and a mammoth furnace into which, until recently, a full-time stoker fed a steam heating system of Heath Robinson complexity.

Here the charity carried on educating the sons of seafarers (merchant and Royal Navy). Later, it included grandsons and, eventually, in 1991, girls, plus “non-seafarer” pupils. Seafarer fees are still means-tested, with the result that most RHS families sign cheques so small as to be unrecognisable to most parents of public school pupils. Thus a child from a primary school in a working-class area of Portsmouth lives alongside the progeny of an admiral, a landlubber whose mum was a Wren, and a full-fee non-seafarer fresh from prep school.

The “total immersion” of boarding offers enough alternative pecking orders and pastimes for the children to seem unaware of how unusual such social mixing is. Apart from the ceremonial “No. 1s” worn for parades, the grey school uniforms are issued to all from a quartermaster’s store.

Moreover, the ability band is far broader than in other independents that hover above and below RHS in the league tables. The sixth form contains those who do well to get D grades at A-level, as well as Oxbridge entrants (six last year).

My own son and daughter were pupils until 2001 and 2002. We supposed there was a slight risk they’d come out with a yen for uniform (they certainly learned to iron), but although the school still provides recruits for the services, for many children a dose of marching, flag-hoisting and calling the prefects chief petty officers merely confirms a civilian bent. My daughter fondly describes the summer “divisions” on the parade ground as “like being in the biggest ever open audition for a Village People tribute band”. As for the seafaring, every new pupil gets a week of sailing on river and reservoir, and neat little land-yachts whizz around the parade ground.

Mr Ward is a lean, restless man approaching his mid-fifties with a chequered career behind him. When he was weighing up the RHS job, he parked his car a mile away and walked along the sea wall with his wife, Jane. “I knew the school a little,” he says, “from working nearby and bringing sports teams for matches. It seemed a strange place in those days - cut off, never in the local papers, with rather old-fashioned looking children.

But always happy. Walking round on a crisp winter morning with the sun on the river I thought, ‘yes’.

“If you’ve got structures of discipline and behaviour in place, you can add on fun, flexibility and better pastoral and academic systems. If you haven’t got the basic discipline, it’s much harder work.”

His first years involved the usual round of staff changes, although the school still has long-serving teachers. “I inherited some superb people who add real character and stability to the school and have supported me brilliantly. Mr Chipses are great, as long as they go on delivering the goods.”

RHSis not for the half-hearted. All staff live on site during term time - there are 103 houses and flats - and Mr Ward insists that everyone, including department heads, does boarding house duties - supervising, organising social events, and generally keeping order. He created small tutor groups in houses instead of a form teacher system, so that each individual’s academic life is supervised by someone who also understands that child’s friendships and hobbies.

He has served as chair of the Boarding Schools Association, but is pragmatic. “Bad boarding is a disaster. Excellent boarding gives a lot to those children it suits. I interview them all, and if I think the parent is imposing it, they don’t get a place.” His attention to detail is particularly necessary now, with each member of staff being briefed about pupils from the 50 or so services families who have parents who may be heading for the Gulf. “We don’t make a big thing of it or emphasise it all the time in assembly,” he says. “But staff will be talking with individual children, and making certain allowances.”

Nicholas Ward’s background is firmly in the state sector. After leaving Wolverhampton grammar school, he read engineering at Leicester University, because “I liked maths and working with my hands”. He graduated in 1971 and decided to be a teacher, spending five years in the maths department at Lancaster Royal grammar (then a state boarding school) before retraining as a solicitor. “We had bought a barn to convert. We moved out of the nice, warm boarding house, my salary went down from pound;4,000 to pound;2,000, I got up at 5am to study for a postal qualification before going to work as an articled clerk. We lived on baked beans and cornflakes, and Jane had to carry the two toddlers up a ladder to bed,” he says.

After two-and-a-half years he qualified as a solicitor and Mrs Ward might have expected to be able to sit back and watch the fees roll in. “But I thought, ‘Hey, this isn’t very interesting.’ I heard about a job at another state boarding school, Ermysted’s in Skipton, where the housemaster had just been killed by a disturbed 12-year-old boy with a penknife. I like the Dales, so we applied.” (I glance at Jane Ward, who seems as unruffled by such strange reasoning now as she was then. “If he’s happyI” she says. “I like schools anyway.”) So in 1979 he took on the boarding house at Ermysted’s, with 50 boys to amuse in the empty weekends. “It was a family atmosphere and very hands-on.

Once, our old dog disappeared into the kitchen and laid into a lump of meat that was supposed to feed 50.” When the LEA ended boarding three years later, he looked around for another school.

It was Framlingham college in Suffolk, and a culture shock. Although the work - setting up a craft, design and technology centre and running a boarding house - was congenial enough, “some of the kids were a surprise”.

He had never encountered the toff mentality. “A few children gave the impression that you were staff - doing a job because their father was paying your salary. But I did enjoy it. Most of them were great.” After five years he “mutated” into bursar. “Fascinating. As a schoolmaster you get contemptuous of worldly things like money. It does you good to see the realities of a budget. But I couldn’t have been a long-term bursar - I’m too opinionated.”

In1991 he moved to the headship of Bentham school, also in Lancaster, which, although an independent, took 11-plus successes from two LEAs and, after Framlingham, seemed pretty broke. “I used to take the first years on adventure weeks - 35 of them sleeping in village halls. In the holidays, Jane and I concreted the classroom floors.” After four years, the RHS job came up.

Mr Ward has taken the roll from 595 pupils to 680, 40 per cent of them girls; the school is now oversubscribed, besieged by seafaring and full-fee parents alike. He modernised the pastoral system, eradicating the last traces of the rough old “lower deck culture”, in which seniority was all, with older boys able to push in front of younger pupils as a matter of right. “It’s a simple philosophy: happy, well-looked after children, content in their surroundings, but within a structured and disciplined environment. I also rejected flexi-boarding. This is a niche market, but it works.”

The memory of a minority of boarders marooned during empty weekends at his first school makes him adamant that, with the short terms and multiple activities of RHS, full boarding works. “Obviously, if a child needs to draw breath and see his or her family, we never impede a trip home - but not to go clubbing on a Saturday night.”

He shifted the balance of power from heads of departments to housemasters and housemistresses. “If you get a head of department who’s not brilliant, things limp on. But if the wrong person’s running a house it really affects children. We’re a serious academic school, but welfare comes first. And it’s harder running a boarding house now than it was 20 years ago, because children are more indulged at home, parents expect you to rein them back.”

There are fewer than three expulsions a year, despite zero tolerance of drugs and in-school sex.

Nicholas Ward’s successor will have a particular reason to be grateful, apart from such entertaining add-ons as a radio station and a small fleet of 22ft yachts skippered by the children. The government of the school has been modernised, too. Its constitution is still unique: Greenwich Hospital holds the purse strings, under a director who is either a career civil servant, or, the latest appointment, a retired admiral. Its sole trustee is, ex officio, the Secretary of State for Defence. (I would like to see the face of a new defence secretary, proudly surveying his new fiefdom of tanks and warships, when he is told: “Oh, and there’s a boarding school in Suffolk, too.”) But under a particularly enlightened director, David Heyhoe, Greenwich Hospital has, over the past five years, given the head and governors the autonomy enjoyed by other independent schools. “When I got here, they were still basically a rubber stamp,” says Mr Ward.

But in 18 months it will all be over. “It’s right for me to go. The new head? I suspect probably someone who’s had a headship, and ideally boarding experience. A spouse would be good, too.” Jane Ward has acted as counsellor, diplomat, and creator of the school’s community service programme.

And how would he recommend the job to his successor? “It’s wonderful. I like the mix of children. I like the way that you would have no idea what anyone’s background was unless you’d read the file. My own life means I don’t find it hard to deal with non-traditional boarding parents.”

As for the experience of being saluted on a parade ground by 680 pin-smart children - what effect does that have? “Apart from the megalomania? It’s very moving. It’s always marvellous to see kids doing anything well, whether it’s the plays, the radio station, the choir at the Albert Hall or the corps of drums doing mess beatings. It sends a shiver up your spine.

And up there on the dais in divisions, when your mortarboard blows off, you can feel hundreds of stifled grins all around you.”