Each of the sketches in ink and oil at the Fine Art Society bears a censor's stamp. They were produced by one of the camp's 3,000 inmates in the First World War.
The artist was Rudolf Sauter who, like most Germans and half-Germans in Britain, was imprisoned with his father Georg, a professional artist (who is represented at Leeds City Art Gallery).
The images reflect the monotony and far from luxurious conditions - the washing tents, the sleeping quarters, the kitchens. However, they do not go as far as a fellow inmate's descriptions, in one of two manuscript memoirs at the Imperial War Museum: he wrote that buckets in which soup was served were also used for washing the floor, and described how on 'foggy days . . . the doors were not opened for four days, the stench became unbearable'.
Rudolf Sauter did not follow an artistic career after being freed: there was no need, for he became financially independent after inheriting a share of royalties from John Galsworthy. Sauter, who had become the novelist's secretary and amanuensis, married Galsworthy's sister. However, his father, Georg, who had spent 20 years of his life in England before being interned, was so disgusted at his treatment, that he returned to Germany and never saw England again.
Peyton Skipwith, of the Fine Art Society, said: 'Alexandra Palace's role as an internment camp is largely forgotten, although there was a widely reported story at the time that during a Zeppelin raid, one of the airships landed on a terrace at the palace, and sailed away again filled with German prisoners before the guards could even lace up their boots.'
The sketches, found at the artist's family home, will be for sale (prices from pounds 250 to pounds 950) at the Fine Art Society, London W1, from 7 June.