Hello All
I hope that I can post this link without infringing any of the forum rules.
The Guardian newspaper in the UK has a running feature called Guardianwitness in which it invites people who have letters, stories or photos from any family or friends who were involved in WWI to share them with fellow readers. If you go to the following link and scroll down
https://witness.theguardian.com/assignment/52751e38e4b01fc33230d4aa?INTCMP=mic_231930You will see two small, somewhat crude, hand drawn sketches of an HP 400 (the images can be enlarged slightly). Whoever submitted the material has suggested that they are in one of four notebook diaries kept by a Jack Chalkin, who became a prisoner of war when his aircraft came down during a night bombing raid.
Presumably details of any such loss could be verified, but at the very least they are evocative period sketches.
Best wishes
Nigel