(Barn) Swallow
Hirundo rustica

Swallows are a familiar sight of the spring and summer months in Britain, after over-wintering in Africa. They are expert fliers and spend a lot of time on the wing hawking for insects. They build nests under the eaves of houses and other similar places out of mud and spit.
 

1-2: Billericay, Essex, 20/05/2006.