First ever Pacemaker model, the 5MO - a 5-valve broadcast band mantle radio.
Likely the only wartime Pacemaker model, with the 515 and 515.2 coming out at wars end, once domestic production kicked in again. It would have been available through to 1942, but at that time most factories switched to producing equipment for the military and so whatever stocks were left would have sold out, leaving the fledgeling Pacemaker brand in limbo for a few years.
The code appears to be in the same style used by Akrad Radio (valves-type-year, 5-Mantle-1940 or 5M0 in this case) which is unusual, although it could be 5MO (oh, not zero). This is probably the last of the oddball coded radios from Collier and Beale as they moved to a code system of valves-bands-year around this time, which remained in place until 1957 when they started using actual names for their models rather than codes. Previous model codes had not been standardised, but typically always started with the number of valves in the set.
Intermediate Frequency: 465kc/s
Frequency Bands: 1
Chassis Notes(most schematics can be clicked to download a full size version)
Service information (cb-model-5mo-pacemaker-5v-bc-ac-1940.pdf) here
General Construction Notes for Collier & Beale Ltd:
Model numbering followed no real sensible scheme until around 1940 - and prior to 1934 apparently no model numbers were assigned at all.
From 1940 a 3- or 4-digit system was employed where the first digit indicates the number of valves, the second digit is the number of bands and the third is the year of manufacture. From 1950 the last digit became two digits, eg: 5151 is a 5-valve broadcast-band only from 1951.
From 1957 model numbers were replaced with model names, ie the Pacemaker Buffalo - which makes the year of manufacture hard to determine unless service info is consulted (although C&B often released service info after the radio, and the date on the service info was for its release, not that of the model.