Below a model of the damage to the new building after the air raid on 19th Nov 1940,the M20 assembly line was not damaged but the two other blocks of the building were hit.
Maybe the M20 assembly line wasn't damaged after the November 19th air raid, but it did have its effect on the production of the M20. When I look in the ledgers, the production was going strong until November 19th 1940 (approximately WM20.30000). Some bikes were despatched the days after the raid, but then we have a gap until the end of December! It looks as if the production of the WM20 was halted for a month due to this air raid!