Wikipedia claims 12th Royal Lancers in France and 11th Hussars in North Africa.
Staulan, I owe you a large and public apology. Another member of AP has contacted me to confirm your original solution - it's the 12th Royal Lancers in 1939/40, with the BEF in Northern France. My original image source claimed that the vehicles were being used by the Home Guard, but after I said you were wrong, I looked hard at the photo, and I must admit that the buildings looked a lot like they were French!
So a point to you, for good research and a correct answer.
(The British Expeditionary Force in France had the most inadequate equipment you can imagine - I don't think those armoured cars would have done too well against a Panzer division.)