Thanks for sharing those photo's from those well made clocks, with proper clock works mechanisms.
I rather see brass and proper metal than all the plastic junk they sell nowthese days which seem to last only a few years, or less most often, Clock batteries for back up in power outage also very unreliable.
My guess is that these clocks are from around 1930's, or early 40's.
The product of rotation, excitation and flux produces electricty.
I haven't looked at the clock in a while, but if I remember correctly, behind that little plate is the ususal connections for the line and loads. I can get the old clock out of storage and get more pictures for you if your interested. The pictures were on my computer but I took them about a year ago. I just remember to find them again and send them to Trumpy. Thanks Trumpy!
I would guess the age as slightly earlier. I used to have some Sangamo timers from the late 1930s and they looked much more "modern" than that. I assume it uses a mercury switch, under the plate with the keep level instruction on it. About ten years ago Sangamo ran a competition in UK to find the oldest of their products still in use. They were clearly interested in their history then, and could perhaps be interested in seeing those pictures.
If you know anyone in the UK from Sangamo and they are interested, please let them or myself know. They can have the pictures or whatever if they are that interested. They can e-mail me through this website, I think.