In James Taylors book, he mentiones that rear headrests were optional extras on the saloon only. I have a P6B waiting bebuild with rear headrests and found that these will fit within reason on my Coupe. They will touch the rear window, but improves rear safety and comfort. And looks quite nice, I think. I dont know if these rear headrests on the P6B are the same in fact for the P5B, so that Rover just did not like them to touch the window or ?.
The rests I had were black but as my interior (no, not my interior - my Rovers interior) is cream, my wife made covers for them, in matching color that can be washed. She is ssoooo friendly !!!