Thanks to JDK for forwarding this interesting image. It's the front cover of Bomber Command: The Air Ministry's Account of Bomber Command's Offensive against the Axis, September, 1939-July, 1941 (London: His Majesty's Stationery Office, 1941) (written by Hilary Saunders). So it was part of the same series of propaganda pamphlets as the more famous The Battle of Britain, aimed at informing the British public about how the air war was being waged.
Why is it interesting? It shows a British bomber (a Whitley, it looks like) high over a German city, looking down. The raid is evidently just beginning: the docks are on fire, a bomb seems to be exploding somewhere downtown. Tracer fire and searchlights are seeking out the enemy. In composition it bears an obvious similarity to the (still more famous) German photo of a He 111 over London. The origins of that are still unclear (at least to me), so it may or may not have been an inspiration for Bomber Command's cover. But it clearly projects the same impression of menace, of power.
I think it's also having its cake and eating it too. The Air Ministry was always careful to say that Bomber Command only struck at military objectives, as international law and neutral opinion demanded. Yet its communiqués, and more especially newspaper reports based upon them, often gave the impression of more indiscriminate reprisal bombing, which a vocal section of public opinion wanted. The cover of Bomber Command does this too, it seems to me. The docks are clearly a legitimate target, but there's nothing to identify what the other bombed area is. More generally, in showing the city literally beneath the bomber's wings in this way, it suggests that the clearly-visible streets and buildings are all valid targets too. So whatever the text might actually say, a reader could interpret this image to mean precision bombing or morale bombing, as they preferred.
Image source: AllPosters.com