muly1976, I think you get the prize. The description, symptom profile and cause all seem to match the problem. It would also back up my assumption that cycling has strengthened particular muscles and tendons in my legs, while leaving others under-developed for running, thereby destabilising the patellar.
Today has seen some relief from the pain. Hopefully increasing my walking distances will help in rehabilitating the muscles that I've neglected, and following some basic stretches and exercises of the leg will get me back on track.
Presumably most cyclists would agree that cycling and running are not mutually exclusive activities? If done sensibly is there anything to prevent the leg muscles, tendons etc developing to accommodate both without risk of injury?