Tom, thanks for the info. How sure are you that they were Peregrines? Kestrel chicks can look similar, and I've already checked two nests this year that were not the supposed species, but a much commoner one!
In reply to Adam Long: i'm no twitcher but pretty certain was a Peregrine my climbing partner more clued up on such things thought so. The other birds went very quiet when the mum was in the air and never saw it hovering which is a kestrels party trick.