I've recently joined a group of volunteers guarding the wellknown peregrine site nr Carnforth. This was only my second visit to the site, where the female is now on the nest. It was a great opportunity to study the birds without disturbance, and to watch both male and female giving excellent views whilst drinking tea and eating homemade cake (thanks hunny!)
Female bird (below). She is somewhat larger than the male, most noticably so in flight and also is distinctive in that she has paler grey plumage on the back, with buff/sienna tinging to most of her coverts.
Male Peregrine, below
He is generally darker in tone, a more gun-metal appearance with cleaner lines, lacking the pale wing coverts of the female.