The (Eurasian) Sparrowhawk is a common resident throughout UK, most of Europe, north Africa and parts of Asia and is a migrant/visitor to most of the rest of Eurasia.
The male Sparrowhawk, above, has grey plumage on his head, back and wings with pinkish cheeks and a rufous brown, horizontal-barred front on white with a white vent.
Sparrowhawk with Goldfinch
The female Sparrowhawk has brown plumage. So they don't compete, she is much larger than the male and eats larger prey (birds as large as pigeons). TV aerials make good look-out points.
The male is smaller and more agile and eats mainly sparrow-/finch-sized birds. They also have eyes in the back of the head.
Sparrowhawks swoop through gardens and woodland chasing prey, unlike Kestrels which hover high and dive. Almost all prey is avian, unlike Kestrels which take voles/mice.
WARNING: PHOTOS ON THE FIRST LINK ARE GRUESOME -- NOT FOR THE SQUEAMISH OR BEFORE A MEAL