Hi Grahame
According to the Lucas catalogue – the 1948 Citroen used a 75066A motor which is an 12V , 120 degree variant of the SW4 Model.
This was also used on contemporary Austin 10 van and 12, 16, Hillman Minx, Daimler 2 1/2, Humber Hawk Imperial, Pullman, Snipe and Super Snipe, Jaguar 1 1/2 litre, Lanchester LD10, Lea Francis, Morgan Plus Four and Morris 10.
In 1949 the part number changed to 75152A which was shared with a similar list of cars which also included Allards, Alvis, Armstrong Siddeleys, Jensens, Jowetts and Sunbeams. This was a 12V 130 degree variant of the CRT Model.
Details here:
and
Regards
Chris