This is the eleventh day of the eleventh month, and the nation's focus is here in Whitehall, both today and on the nearest November Sunday morning. Distant hum of traffic, scurrying leaves. Black coats, red poppies, chill breezes teasing flags and white hair alike. The Cenotaph is the physical core of a nation's remembrances, commissioned from Edwin Lutyens in July 1919. The architect won his own battle, against those who wanted a giant cross, with spectacularly complex geometry. There isn't a straight line in it- the verticals meeting at an imaginary point 1,000 feet above the memorial. The horizontals are all arcs of a circle whose centre is 900 feet underground, and author H.V.Morton saw the empty recess in the Portland stone quarry not long after its removal. 'Cenotaph' is Greek for 'empty tomb', a sepulchral monument for bodies elsewhere, and is a word Lutyens learnt from his great gardening friend Gertrude Jekyll. I took this photograph for my little book Lest We Forget, and had a very odd experience. Waiting for the coincidence of sunlight and buses, I looked down to see that the batteries, and indeed battery cover, from my camera were missing. I found them in a neat row on the steps of the monument, and I shall talk more of my encounters with war memorials here in June next year.