Help identifying a hawk please

Hi, just saw a hawk or some such but can’t quite work out which it was. Was having a disagreement with an adult crow. Was fractional smaller, was dark colouring (due to angle and height I couldn’t see exact). Had a smooth squared/rectangluar tail and pointed sleek wings. Had a high pitched repetitive chirp noise. Was trying to either land on the high Ariel thing or the crow has a nest but I know the crow babies are all fully fledged and nearly adult size now so not in the nest. Think it may have been a Hobby as the images I’m finding for the bird in flight look like that but going on alarm sound on a bird app I have it sounded like a female kestrel. I’m in Essex SS8 postcode if that helps.