vested so much time and emotional energy in the school, we'd made such improvements over the past 10 years. To see it destroyed overnight was devastating."
Even more devastating was the suspicion, soon confirmed, that Watchorn's school was a victim of arson - one of 1,400 such attacks on schools in Britain every year.
But few arsonists have "enjoyed" such spectacular results. Two of the three main blocks were gutted; all school and academic records were destroyed; and many staff lost a lifetime's teaching materials. Pictures of charred desks under collapsed rafters made the national papers and rebuilding costs were estimated at Pounds 10 million. The shock to both the staff and the 900-plus pupils was profound.
But if the arsonist had hoped to close the school, he was to be disappointed. "We made an instant decision that the Year 11 pupils would come back the following Monday," said Mr Watchorn. "Even though they didn't have a school, we would accommodate them somewhere. We got letters out to all parents, through the further education college. " Rumour had it that the Abraham Moss fire was started by a disaffected ex-pupil, although no charges have ever been brought. Every day, three schools will suffer an arson attack, according to the Arson Prevention Bureau, and the number of attacks has increased steadily over the past 10 years. Last year's 1,400 incidents cost more than Pounds 50 million.
Research by the bureau - set up by the Home Office and the insurance industry - found the typical arsonist to be a pupil or ex-pupil aged between 10 and 16, nine out of 10 of them male. But the good news is that education initiatives developed by the fire service have had encouraging results in deterring fire-setters.
Graeme Ferguson leads the community safety group of the Lothian and Borders Fire Brigade. The group targets pupils of nine and 10 in 53 primary schools, using a mobile classroom which visits each school for two days, staffed by a teacher seconded to the fire brigade. Children hear about the dangers of fire in the home, learn how to call the fire service and find out in graphic detail what the effects of hoax calls can be - diverting firemen from a scene where children are trapped in a burning house, for instance.
Mr Ferguson insists: "Most definitely we are preventing fires. They have steadily come down, where in other areas figures are rising. I think it's making the children aware of the dangers, in a very hands-on and interactive way."
Hoax calls have come down by more than 60 per cent in one Lothian and Borders area, and the group is working to further reduce "wilful fire-setting".
Most children are interested in fire. It is a natural element, beloved of generations of campers. Educational psychologist Andrew Muckley, of Redcar and Cleveland, is an expert on fire-setting and has worked with many young arsonists. "Fascination with fire is a normal thing," he says. "It needs to be in our education somewhere. It wasn't necessary 50 years ago because everyone had one at home, and they probably lit it before they came to school."
Often children's risky behaviour is simply the result of a lack of awareness. Few five-year-olds, says Mr Muckley, would believe that one match could burn down a whole house. He describes a potential arsonist who starts off near his home, playing with matches and lighting leaves or paper in the garden. With education, he can learn that matches are "a tool not a toy" and have his interest channelled into supervised barbecues or bonfires. This child is dubbed the "curiosity fire-setter".
More dangerous is the "angry or revengeful fire-setter". These children typically have poor communication skills and start fires to relieve feelings of anger. Muckley says: "He's naughty at school, the teacher has told him off, and he gets the idea into his head that he's going to burn the classroom down. But we now know enough about fire-setting to address it."
In Lothian and Borders, fire officers work individually with the handful of children who are persistent fire-setters. Ferguson cites the case of "Simon". A neglected child in a chaotic family, he became obsessed with Fireman Sam and the TV series London's Burning. He set fire to his own bedclothes at age three; the fire destroyed the bedroom and the family were rehoused.
By five, Simon was setting fire to anything that burned - his bedroom carpet, posters on the wall, bits of scrap paper. When Mr Ferguson paid his first visit to the family, even the soles of the child's trainers had been melted after he had stood in the embers of a bonfire. The fire officer talked in detail to him about fire and its risks, got a smoke alarm installed in the house and referred the family to the psychiatric services. Fire education for the child was then combined with a behaviour management course for his parents, who hadn't effectively kept matches and lighters out of reach.
This one-to-one approach can be used with older children. Alan Stoker, senior fire safety officer in Greater Manchester, says his team has worked with 18 young offenders in the past three years, none of whom has committed arson again. "One of the big issues is that they don't understand what fire is about - the speed of it and the devastation it can cause," he says.
Alongside specialist education, schools can reduce risks from arson through a range of security measures. Unoccupied at night and often isolated or at least not overlooked, schools can provide a soft target. St Brigid's Roman Catholic School in Knowsley, Merseyside, recorded seven fires in a spate of attacks in the early Eighties. The school "burned down bit by bit", says current head Gill Price. The final fire, in August 1985, destroyed the school completely.
St Brigid's re-opened in 1988, as near to arson-and-vandalism-proof as a school can be. The two-storey, square building, housing 200 primary pupils,offers no hiding place; all entry points are alarmed, the drain pipes are on the inside of the building, and the shatter-proof polycarbon windows have steel shutters. The whole is ringed by a three-metre security fence.
Yet Mrs Price, head for the past two years, insists it doesn't feel like a fortress. "It's lovely. It's designed to be child-friendly; the paintwork is red, the windows are port-hole shaped and the security lights are attractive, with an orange glow. The things that are in place here make running the school so much easier. I'm not using my budget on vandalism, fires and broken windows. It's all going on the children, and they do feel secure."
Rebuilding is well under way at Abraham Moss, where pupils now stream around a huge, fenced-off building site, to the roar of diggers and the shout of men in hard hats. The school is currently housed in the one block that survived the fire, plus an elaborate prefab which provides a rabbits' warren of temporary classrooms and science labs. The insurance policy provided only for the replacement of "like with like", and the local authority, pleading poverty, was unable to chip in. However, after the fire, pupils wrote to Tony Blair to ask for help and last week the Education Department agreed to make a special grant of Pounds 1 million to help with the rebuilding costs.
Work on the new Abraham Moss school is expected to be complete in time for the start of the 1999 academic year. David Watchorn will be first through the door.
'How to Combat Arson in Schools' is available free of charge from the Arson Prevention Bureau, 51 Gresham Street, London EC2V 7HQ. Tel: 0171 216 7474 'Addressing Fire-Setting Behaviour' by Andrew Muckley is available from Redcar and Cleveland Borough Council, 5 Turner Street, Redcar TS10 1AY, price Pounds 50