Cockchafer Beetle

A large beetle, also sometimes known as a Maybug, Doodlebug or Maybeetle.
It's one of the largest beetles found in the UK (about 25-30mm) and makes a deep humming sound in flight.
They have fan shaped antennae, males having 7 "leaves" whereas females have 6. This one pictured that was crashing in to my window is male I believe.
Historically these bugs have been a major pest for agriculture.