Kestrels are small, as are male sparrowhawks. You almost certainly saw a female sparrowhawk. Peregrines consider pigeons to be an easy lunch, to give an idea of comparative size. Peregrines are slightly less common than an available black cab in a thunderstorm in London.
I was lucky enough to see a peregrine diving on prey of some sort in north wales some years ago. I could see it wheeling above a valley I was walking along the top of, then it folded it’s wings and dropped, at a ridiculous speed. Impressive stuff.
Kestrels are small, as are male sparrowhawks. You almost certainly saw a female sparrowhawk. Peregrines consider pigeons to be an easy lunch, to give an idea of comparative size. Peregrines are slightly less common than an available black cab in a thunderstorm in London.