The Kent bat box (above) is a very popular choice with bats and they have the added advantage in that they can be checked from the ground. This is one on the flank wall of the barn in Richmond park and both compartments are being used as can be seen from the fur staining within the middle of the entrance slits. These can be made very cheaply from wood offcuts and are a cheap alternative to the Schwegler 1FF. More on bat box choices can be seen here.
Martin's bat box suggestions
Bats have been active for longer than usual this autumn, due to the warm evening temperatures. Insects have been much in evidence rising from the water column, particularly along the Hogsmill and the Beverley Brook. Last Friday we had three bat species on Epsom Common: Leisler's bat, Common pipistrelle bat and Daubenton's bat.