Starling

Look at these bad boys perpetuating the stereotype! Note the raised crown feathers in the third picture just before he loses his temper. (I think it's a chap. If you look closely at the base of the bill it is light blue-grey. In ladies it's just paler than the rest of the bill. More obvious perhaps in the bird that gets attacked.)
Starlings, Sturnus vulgaris, are an apparently common bird which is on the British Red List, meaning that it is of greatest conservation concern. The reason is a population decline between 1966 and 2004 of around 80%. That seems an astonishing statistic, but it is borne out in other European countries, making it a Species of European Conservation Concern or SPEC. 
As most people know, the collective noun for starlings is a murmuration. Another one is an affliction. Winter flocks can reach enormous proportions and witnessing them coming in to roost is surely one of the great spectacles of nature; up there with watching the lions in the Serengeti. Check out the video below, find out where you nearest monster roost is, and get down there one evening before they disperse for the season.