Bird of Prey Silhouette - London

I took these pics today at Kew Gardens, West London. It was gliding & circling high and not easy to judge size, all I can give is a very unhelpful b/w Kestrel & Buzzard in size.

I've looked through my books and can't find anything quite like it.

The pics are a 100% crop and lightened as far as I could.

any ideas?

thanks

Tony

Source: http://www.birdforum.net/showthread.php?t=224803&goto=newpost

lord monckton andy kaufman october 21 2011 ohio ohio john beck john beck