In the summer of 1915, shortly before his death on the first day of the Battle of Loos, a 25-year-old subaltern in the Argyll and Sutherland Highlanders called Douglas Gillespie sent home a letter from the Western Front. ‘I wish that when peace comes,’ he wrote,

our government might combine with the French government to make one long Avenue between the lines from the Vosges to the sea … I would make a fine broad road in the ‘No Man’s Land’ between the lines, with paths for pilgrims on foot, and plant trees for shade, and fruit trees … Then I would like to send every man [woman] and child in Western Europe on pilgrimage along that Via Sacra, so that they might think and learn what war means from the silent witnesses on either side.

It was one of the most appealing ideas for commemoration to come out of the war and one, sadly, that had about as much hope of happening as Churchill’s dream of preserving Ypres as a permanent ruin. The French and Belgian governments had been immensely generous in their provisions for Britain and her empire’s dead, and yet for very good reasons they were a lot less keen on preserving the scars of German occupation than later generations of battlefield tourists might wish.

With only a minute percentage of trenches surviving and those ‘silent witnesses’ tidied into the cemeteries of the Imperial War Graves Commission or piled into the grim ossuary of Douaumont, Gillespie’s vision must have seemed more remote than ever when the historian and educator Anthony Seldon first came across