Can you identify this bird of prey?

I was leaving work today when i heard a strange bird call, so i looked around to see a bird of prey flying fairly low towards a tree. I knew straight away it wasnt a kestrel and im pretty sure it wasnt a sparrowhawk either, but after doing a but of research i am now stuck between wether it was a hobby or a peregrine. Once it landed and was sitting in the tree you could see it was somewhat bigger than a kestrel and noticed It had distinct eye markings and a very uniform grey coloured back and pale front. There is a small piece of grassland near to my office which is on a small industrial estate on the Norfolk/Suffolk border and it is very out of the ordinary to see anything other than crows and pidgeons! I appreciate the photo isnt great but its all i could get. Any comments are appreciated!