Sparrowhawk over Streatham common, possibly two hobbys

I saw the sparrowhawk fly onto her nest in Bedford wood, the nest has small white feathers entiwined in its edges, I wonder if they are from chicks (too soon?) or from other birds. In the early evening I saw a Sparrow-hawk over Streatham common, and possibly a pair of hobbys, flying across Norwood Grove, at first I thought they were peregrines at first, but looking them up I now think they were smaller than peregrines, probably sea gulls ! but I'm sure the second one was a male with some redness underneath...