These are the coloured doves of Faringdon House. The eccentric composer Gerard Tyrwhitt (Lord Faringdon) turned the doves on his estate rainbow-coloured using a harmless vegetable dye, and the National Trust keeps up the tradition every year at Easter.
Berners also trained a parrot to walk inside a bowler hat, so as to give the impression of the hat crossing the floor unaided, took tea with a giraffe, and managed to be good friends with that nasty fascist Diana Mitford/Mosely.
The folly he built, Faringdon Tower (not to be confused with the Beckettian Barrington's Tower), carries the notice 'Members of the public committing suicide from this tower do so at their own risk.'
The back of his Rolls Royce was fitted with a small keyboard, enabling the musical lord to play and compose on long journeys. He was Stravinsky's favourite English composer, and his work can be heard on the 1946 film of Nicholas Nickleby.