Raptor ready

I’m pretty certain I saw a peregrine falcon yesterday, even though we are on the limits of their range as reported by the RSPB: in any case, a fairly large falcon with pointed, scimitar-shaped wings and a long, largely straight tail was hunting over a meadow just north of Audley End house. I watched it for nearly five minutes as it gradually ascended. I was wearing polarised sunglasses so the colour was uncertain but what I saw were areas of silvery pale on the breast and body. It was definitely not a kestrel which is smaller, has straighter wings and a less strait tail. Nor did it fly like a kestrel, which tends to move briskly between hovering stations. This bird was ranging over the sky. It had a single call repeated in burst of five or six in two different pitches which is not on the RSPB site but less dissimilar to one of their peregrine posts than anything else. But if it was a peregrine, where is it nesting? The country round here is notoriously short on cliffs and even skyscrapers.