Almost 60 years ago, a 12-year-old boy called Bill Sharp was suffering from boredom during a history lesson. To distract himself, he wrote his name and the date - 25th Sept. 1943 AD - on a scrap of paper, folded it into a tiny rectangle, and (no doubt first glancing up to make sure the teacher wasn’t watching) surreptitiously reached across to the wooden sideboard adjoining his desk and slid the piece of paper between the underside and a narrow supporting ledge.

Bill Sharp went on to spend a lifetime working for the National Farmers’ Union. His scrap of paper lay undisturbed under the sideboard ledge for 58 years - until 2001, when he attended a reunion for former pupils of his old school, Tormore, a seven-to-13 boarding school that specialised in preparing boys for public school. The reunion was only for boys who attended the school between 1940 and 1945, and it was not held at the school’s premises in Deal in Kent, but at the Vyne, a 16th century stately home in Hampshire, now owned by the National Trust.

The Vyne was where Tormore school was evacuated, at a day’s notice in May 1940, when coastal Deal suddenly came dangerously within range of Hitler’s guns, which were approaching the coast of France. On evacuation day, 52 boys and their teachers were loaded into buses; beds and desks went into trucks, and the whole caravan set off to Hampshire, stopping only for a picnic on the way.

On the first night, they all slept on a long line of mattresses between marble busts in the Vyne’s Oak gallery.

On the next day, they were back at their desks, arranged in three different forms along the Stone gallery, with the top class sequestered in the elegant Tapestry room.

It was in that setting, in 1943, that 12-year-old Bill Sharp wrote his note for posterity - returning during the reunion to find it again, with the help of his penknife, exactly where he had left it. Bill recalled:

“I specifically remember writing on this piece of paper and hiding it under the sideboard where the headmaster used to put letters that had come for us.”

He pointed to the evidence of wartime paper rationing, which meant that even before he found another use for it, his history test had been written on a reused official form. “I thought maybe someone would find it one day.”

Of course, children are forever writing their names on desks, books or scraps of paper, and hiding their secrets and treasures too. But maybe it was the insecurity of wartime that made Tormore’s boys squirrel away so many notes, drawings, letters from home, cartoons and comic scraps destined for posterity in so many different hiding places in the magnificent old house: under floorboards, up chimneys, in cracks in the furniture and the wooden panelling.

Bill’s piece remained in its hiding place, but other snippets of history were uncovered three years ago, when a majorrefurbishment of the Vyne was underway. Staff publicised the finds, and the National Trust was contacted by old pupils of the school, who added photographs, letters and reminiscences to the evacuees’ secret hoard. The result, in a display created specially for the Tormore reunion but also designed to be seen by visitors to the house, is living history of a particular kind of wartime childhood.

Discipline at Tormore was harsh: the cane belonging to headmaster F G Turner (known to the boys as FidGeT) is on display at the Vyne; so too is a scrap of one boy’s lines, reading: “I must not hum in school I must not hum in school I must not hum in school...”

Evacuation was an added trial for these boarding school boys, who had already experienced the trauma of family separation - some, as young as six, came from army families or had parents living abroad in the former British colonies who were unable to visit their sons for the six years of the war. But it was in some ways also a liberation, says Geoffrey Rowson, 71, horticulturist and Tormore pupil who masterminded the reunion, tracking down 80 of the 120 boys who were at the Vyne between 1940 and 1945: “In Deal the school wasn’t quite Dotheboys Hall, but discipline was strict. We went from this rather grimy building smelling of boots to this magnificent mansion and acres of ground to run about in.”

And the evidence for their running about was still to be found. Before the finds under the floorboards, says the manager for the Vyne, Karen Laverick, the National Trust knew only that there had been a school there. Now it has school photographs, snapshots of boys dragging firewood through the fields, accounts of swimming trips and near-drownings in the lake, letters about boxing matches, reminiscences of the once-a-week baths, cricket on the lawn, “slipperings” at bedtime.

The letters hardly mention the war, but the drawings all depict tanks, helmeted soldiers and aeroplanes. One boy writes of listening to air-raid sirens while on the roof; another writes of German planes dropping anti-radio paper. “As a child one didn’t really appreciate the seriousness of war,” says David Secker-Walker, 69, a former journalist and merchant banker. “We had a map with flags for the movements of the armies in North Africa and we followed it almost as if it was a football match.”

The National Trust has created a stage script with historical notes and classroom activities based on reminiscences of former child evacuees who were sent to some of its stately homes. The War Child is aimed at juniors, costs pound;9.99 plus pound;2.50 postage and is available from National Trust Education, Vector Services, 13Denington Road, Wellingborough, Northamptonshire NN8 2RL. Tel 01933 445600