The barred plumage has me wondering whether this bird wasn't, in fact, a female or a juvenile kestrel. They're browner and more conspicuously barred than the female and juvenile sparrowhawks.
But I'm fairly sure this is a sparrowhawk because of it's behaviour - patrolling gardens - and because it's wings don't appear to be as long and pointed as the kestrel's are. The sparrowhawk has shorter, blunter, wings designed for manoeuvrability, rather than for hovering over open ground.
Ways of Drawing Birds
The difficulty I have in separating our two commonest raptors makes me realise that I don't spend as much time bird-watching and bird sketching as I would like. I once had the excuse of doing nothing but draw birds for 3 weeks, when I was commissioned to produce the illustrations for Ways of Drawing Birds, originally published by The Running Press of Philadelphia.
I drew hens and geese on farms, birds in the back garden and on the local nature reserve, condors at a bird garden, ostrich and humming birds at the zoo and owls at a rescue centre. I also managed to fit in short trips to sketch gannets on the Bass Rock, puffins on the Farnes, eider duck on Lindisfarne and gulls at Flamborough. I even sketched a stuffed jay when I attended a governors meeting at the local school.
I got caught up with the excitement of exploring the world of birds, filling several sketchbooks and writing pages of notes each evening, an exhausting but exhilarating experience.