My personal theory is that they are descended from a group of pigeons that nested in an old nuclear waste container that washed up on the banks of the Thames sometime in the ?80s. Their is an innocuous office in a building on Whitehall filled with filling cabinets and a messy haired man in a tweed suit who has been cataloging their activities since the early ?90s. A pair of MI5 agents engaged on another line of enquiry* have been following a trail of clues that has led them to his door. *A pensive young man (perhaps played by a young Jack Palance) and his domineering, fast talking, sexy female partner (definitely Billy Piper).