I've got one - and 5 cases - we used the cases for 40 years as parts trays - not knowing the cases were clocks - I think the clock is 40's early 1950s - and I think the clock might be a "PAM" type and the case made to fit it.
Interesting 110V 50HZ Warren Master Clock that was sold in the UK - Serial #513 - I have one of date unknown with Serial #401.
110V/50HZ seems somewhat weird in the UK - there are comments by the seller that maybe this came over during WW2?
Link to listing
From our archives (maybe 1940's/1950's) - a 10' diameter tower clock for Dawson Ale and Beer - located on South Huntington Avenue - Boston, Massachusetts USA - Neon-lighted clock hands and dial markings. I believe our #4 Tower Clock Movement.
this is the problem henry warren had when he hooked up synchronous clocks to the Boston power grid. I would think more likely than not your inverter depends on an RC circuit for frequency stability - which are poor for stability but fine for most applications.
I have an article written by an engineer on the commissioning of the Colgate clock - I will have to find it. I believe it started running backward when first put on test.
The Clock was 16' in diameter and blown down in the hurricane of 1938.
One option is that we have provided the case for clients who have obtained mechanical movements - these are the designs of our post clocks the howard and seth thomas are either made from original patterns or molds off an original clock.
Pretty good article on UPS - I think you would want either a line interactive or an offline UPS - finding out the frequency stability when on battery of any of these might be hard, however.
We do make a "Stop" tower clock controller that would reset any AC motor after a power failure - it does...
If you use alkaline, both batteries are the same voltage 1.5 VDC and the current capacity is 1.8 or 8.0 AH respectively - I found smaller AH lithium-ion batteries do NOT have enough peak surge current to run some stronger loads.
Research paper on Time and Frequency from electrical power lines from the NIST
Due to the efforts of Henry Warren, inventor of the Telechron electric clock, electric power companies have been a source of time and frequency reference for the public for over a hundred years. However...