i will probably be wrong, but i don't think those are Vickers.
all the Vickers stuff i see looks like belt-fed and water cooled.
http://www.wwiitech.net/main/britain/weapons/vickers/
http://www.canadiansoldiers.com/vickers.htm
those drum fed guns on the jeeps look more like Lewis guns to me.
http://www.wwiitech.net/main/britain/weapons/lewis/index.html
but the text says they were largely phased out by 1936.
(of course, after Dunkirk, any available working firearm was likely pressed back into service!)
they are unlikely to be Bren guns, which used a 'banana' magazine that went on the top!
http://www.wwiitech.net/main/britain/weapons/bren/index.html
overall, this is a great site for weapons study.
browse around.
ed.