Though it is far too cramped and small, playing second fiddle to a once fashionable photographer — David Bailey in this case, but my objection applies to every other who might have been so honoured, so foolish is this misjudgment of priority. I am grateful to the NPG for this exhibition. It falls between too many stools and concentrates on only one campaign, the long-drawn Western Front, but it is to some degree a reminder of the horrors inflicted by war. My diminishing generation needs no such reminder; in my childhood before the Second World War, on every street in London I could see the living wreckage of the Great War, men limbless, eyeless, dreadfully damaged, selling matches and bootlaces for a penny, or, in hope of a penny, singing (often rather well), playing the accordion, the saw (outside St Mary Abbots, Kensington) — yes, the saw — and a harp outside Tattersalls in Knightsbridge. The fortunate legless might have a wicker chair on wheels, the unfortunate a simple wooden chassis paddled along with the hands. A curious child, I wonder how such damaged beings emptied their bowels and bladders, where they slept, how they could eat. Now I see them only in my memory and in the dreary northern paintings of Laurence Lowry. The Great War did not create a world fit for heroes — it threw them on to the street.

It did, however, establish lasting loyalties and affections. Only once did my stepfather speak of that war, though he fought throughout it — in France, the Balkans, Gallipoli, Mesopotamia and the Holy Land — and that was when I unwisely developed an interest in Lawrence of Arabia (who is among the many not included in this exhibition) whom, I learned, my father had good reason to think “a boastful little shit”. But his loyalty to those with whom he fought was quite extraordinary and to be found in no other of his interests; he joined his soldier peers once a month for dinner, even in the blackouts, the Blitzes and the Buzzbomb Summer of the Second World War, until his death in 1962. I experienced something of that loyalty as a National Serviceman with not an enemy in sight — but had there been an enemy, that loyalty would have been much more intense and lasted longer.

But these are the maunderings of an old man in melancholy mood inspired by the pathos of the young so early dead. As the experience of war in any form, in the armed forces or as a civilian, is now the privilege of very few in Britain, I doubt if many will share my powerfully empathic response to this exhibition but I beg them to try. Having done so, having watched the film clips (cramped and uncomfortable) and perhaps having gleaned something of the inglorious sufferings of the soldier, cross the road towards Pret A Manger and, glancing to the left, spare a moment for Edith Cavell, nurse, executed by the Germans in October 1915, for there is her monument, “Patriotism is not enough”, the inscription — her last words, we are told. And it is not, but how now are we to interpret this Delphic utterance when young Gavrilo Princip’s patriotism proved to be so much too much?

The weakness is a jarring curatorial voice that makes bombastic claims that are quite unnecessary; the pictures tell their own story. But the wall text offers questionable generalities like this: "The appalling consequences of [new] weapons suggested that human nature itself had changed, compassion snuffed out by unbridled cruelty and hatred. Such altered perceptions raised profound questions for artists". Was it really new weapons? Was it really worse than, say, the thirty years' war? And even if it was, why should other horrific conflicts not have caused such questioning? Were changed perceptions really caused by war? Virginia Woolf thought human nature changed in December 1910; why do the curators think it was later? These questions are better left for visitors to ponder. Less would have been more in this otherwise fine show.