To enlarge upon Nigel's cryptic posting, the bikes in the picture are 1919-20 Blackburne 4hp models. The thinking is that, Blackburne being principally an engine manufacturer, these bikes were assembled by OEC in Gosport (not far form Portsmouth). When this picture was taken Blackburne were at Tongham near Aldershot. In 1921 they moved to Bookham in Surrey and all complete machine production was officially taken over by OEC. So, it is possible these pictures come from OEC where the bikes were being assembled before 1921 - which would be proof of that theory, otherwise I guess it is from Tongham. The only other possibilty is some distribution point, but the bikes being assembled suggests not. I doubt the cars have anything to do with it. Coincidentally, in the late 20's Blackburne shared their factory space with a car body refinisher so maybe they did the same at Tongham. The Crossley may be 'the bosses new car'. My final piece of evidence is that the rear-on bike that is clearly not the same as the rest,(belt drive etc- possibly a 350 Blackburne as used in the 1920 TT) has a number plate on the back and the two letters at the top look to me like PA. All Blackburne road test models had PA numbers - Surrey. The later bikes are, I think a 1925 BSA model S 500 and a 1927 BSA. It's a great picture and I would love to see any more John may have, the history of Blackburne is one of my obsessions! Cheers, Rick