In response to Dave's post - we have been looking at a small flock of pigeons at St Brides for years. As with the Martins Haven birds they nest on the cliffs and are a real mixture of plumages, with many looking like pure Rock Doves. However, we have definitely seen a ringed escaped homing pigeon with them which could explain some of the rogue genes! Having said that, several of the farms around here have flocks of feral pigeons, of every colour combination possible, but they seem to stay inland.
Rosemary Royle