Don't mess with these lads! The bike is almost certainly a photographer's prop and the location is down on Madeira Drive in Brighton. I wish I knew more of the social history of motorcycles as beachside photography props. Were they still such a luxury item in the twenties that people sat on them for aspirational pictures or were they just something fun to sit on for a photo? Either way the prop bikes were almost universally rather on the knackered side - look at the bald tyres and dents on this Rudge.