Are we sure they are Dunkirk evacuees & not just the local TA lads? They are sat on a traffic island at the bottom of Victoria Rd (Vic Hill we call it), with Groundwell Road in left background. The traffic island has been altered in the years since the 1940 photo.
I can't remember where the picture came from but the impression I got (I was searching for Dunkirk stuff) was that they had just come home. Great then and now by the way......And you was so quick ! Do you live on Regent St.