I finished my walk at Vauxhall, as my detention on Park Lane had cost the better part of the early afternoon. I hope to complete the walk at a later date. The decision to stop was made, appropriately enough, in the shadow of Vauxhall Cross, the headquarters of the Secret Intelligence Service, MI6. The blazing red spot on the map, denoting a concentration of cameras, is accounted for by this – and by the far more mysterious building at 1 Bessborough Gardens on the other side of the river, blank-faced, festooned with cameras, whose neighbours regularly complain of electromagnetic interference.