That looks like a lot off work you put in this indeed!
It amazes me you could find all this information and can't thank you enough for all the work.
It is still a bit off a mystery this engine, but I have a much clearer picture off wat went on. I'm happy whith the answer you could give me and for now I will assume it was a spare engine from an early contract and it did not come with a frame..
According to the engine book above, engine no. 872 was fitted to frame no. 143 but the frame book entry for 143 shows engine no. 1872 ! :grimacing: It was sent to the War Office on 12/9/1939 though.
Engine 1872 is not shown as fitted to a frame. Presumably 143 should have been entered there ?
Typos! Must have been 1872 and 1868, these numbers would fit perfectly in the 1700 - 1900 range:
The first WM20 was frame number WM20.111, and the first batch (frame numbers WM20.111 - WM20.251) all went to the Ministry of Supply (contract number unknown). Up until frame number WM20.243 there were still no "matching numbers" (engine numbers were chosen "at random" from the WM20.1700 - WM20.1900 range (*).