Ground crews arming a B-29 Superfortress of the 500th Bomb Group at Isley Field, Saipan.
Image source, click image for full resolution.

Final assembly of Mosquitos, 1943.
At the Hatfield plant different models were being produced in batches on the same assembly lines PR.IX, MM 256 (left) was delivered in November 1943 to No 60 Sqn, SAAF, but went missing over Marseilles on 13 May 1944.
Click here for Image source.