For some odd reason that number appears familiar, I can't quite place it but there's a regular 400/4 that visits Newlands corner, near Guildford, when the bikes are there which I seem to have a link in my mind to.
I only usually go there on a Sunday and it's often there parked over the back part of the carpark where all the bikes stop and sits right there for some time, but I've never spoken to the owner.
Could be worth a look to verify, I'm often there around 12 to 3 in the afternoon if I'm passing.