Got this today.
It features an AS 1171 bumper movement - working fine - which Dr Ranfft gives as a redesign of the Harwood automatic.
So dating to about 1940.
And with the rotor moved over.
If you look carefully you can see the little ratchet that winds the movement in one direction only.
The watchmakers will also note that the set lever screw has been attacked by a gorilla (not me). I can't undo it yet, and so can't take the movement out so that I can clean the top of the case properly and replace the crystal.
The case was filthy. No, really!
Anyway, I've no idea how rare or not these are. BTW, a gold Harwood sold on ebay recently for £258 - which didn't seem bad to me, but was beyond my budget. The movements look very different to my untrained eye.