This video from England says about itself:
Lesser Horseshoe bats filmed on a TV screen from a bat cam set up in a roost on Marsland Nature Reserve – a building has been specially converted to accomodate the roost which has built from just 1 over 10 years ago to 106 in 2011. These individuals are being irritated on occasions by a bat fly parasite (can be seen moving over the back of one @ 52 seconds).
Lizzie Platt from Devon in England reports on Twitter today that bats are flying around. Very unusual for December; because of unusually warm weather.
British bats: here.