Change from Low-light to High-light - when?

[gtt1951]

I have a 1951 High-light, registered 15/03/1951. I'm watching a 1951 low-light on fleabay that was manufactured in 1951 (according to DVLA and the seller).
When was the change made from "low" to "high" lights.
The fleabay one does not have a heater so, supposedly, may still be on "syphon" system and no water-pump (pictures don't show this.
here is the link
http://www.ebay.co.uk/itm/151371843024? ... _166wt_959
Regards, George.

[Dean]

http://potteries.mmoc.org.uk/Identification.htm

1950 according to the link.

[mike.perry]

According to my records the car is a very early 1951, SMM 80103. It has the later engine with thermostat housing and presumably a blanking plate and no water pump which was an optional extra with the heater. Those were the days when men were men and women had hairs on their chest. Having consulted "OMM" the chassis number is given as 832024 for single bumper, obviously a misprint, and 83390 for high headlights on 2 door/tourer. American market cars had high headlights from early 1949 and 4 doors always had high headights since their introduction in 1950

[DAVIDMCCULLOUGH]

There were made side by side on the production line a for a time as the high lights were going for export while home market still got the lowlight until approximately February 1951.

[mike.perry]

Not quite true as high light 4 doors were still being sold on the home market until Jan 51. Several batches of 803 4 doors were exported in 1952