I've recorded Madiza glabra - mainly gravid females - close to home (Codford, Wiltshire) and have a few interesting photos.  It occurred in large numbers along with a Chloropid Thaumatomyia notata on the inside of upstairs windows over a period of several weeks.  I'v not seen M. glabra  in previous years and I'm sure I would have done so had it appeared.  There have been no earlier Wiltshire records.  A few items in the literature note that this and related species are attracted to specific chemicals which tend to occur in the domestic environment.  Has anyone else noted similar behaviour?