Richard,
The owner was always insistent it was 1936 but this does not sit well with me.
I wonder if the factory always designated the whole series 12/4 on the plates and the various model designations were marketing department inventions?
I am awaiting an original manual which has on the cover Morris 10cwt, Series "Y" to see if there is reference to 12/4.
Have a look at this info on the Morris 12/4. The mystery deepens! The 12/4 cars were only side valve until 1937. Would a van, not starting production until 1939 have been afflicted with a sidevalve from the past when everything coming down the line had overhead valve engines?
http://www.iamo.org.uk/Models/Twelve...ies.htm#engine
As a spoiler I have just found a Fordson E83 which we know was certainly in service but the lesser power (1,100cc) and atrocious top speed of 40mph knocks it out for any Normandy trip. The Morris advertising may actually be correct about speed and from various sources 12/4 is rated at 72mph top speed with its 1,500cc motor - not many small cars of that era could do any better than that.
Lang