Paul Nash - Raider on the Shore
Image courtesy Glasgow Art Gallery
I have been unable so far to trace a photograph of the corresponding real-life event, if there is one. The aircraft is a Heinkel 111 and it looks as if it came down reasonably intact but has been subject to the action of the tide. As recovery from that location would have been very difficult it may have been abandoned by the salvage teams, who had plenty to do elsewhere.
The background suggests the Dorset coast or the Isle of Wight.