There are only 4 species of net-winged beetle on the British list. They can be identified using Mike Fitton’s excellent keys (from his PhD thesis), which Brian Eversham has updated: Lycidae are keyed out in the Appendix.
They are mapped in Keith Alexander’s (2003) Provisional atlas of the Cantharoidea and Buprestoidea (Coleoptera) of Britain and Ireland, published by the Biological Records Centre and now available to download.
They are included in the Soldier Beetles, Jewel Beetles and Glow-Worms Recording Scheme run by Keith Alexander who may be contacted here, and who would be pleased to receive records and happy to help with any identification problems.
All the lycids are saproxylic, developing in decaying wood. They are all scarce, if not downright rare. The rarest of them all is Erotides cosnardi known from only 10 confirmed British individuals (to the end of 2014). Erotides cosnardi was until recently known as Platycis cosnardi.
In Jon’s words (17th Feb. 2012): “attached is an image of the 4th British specimen of Erotides cosnardi [from Goodwood, West Sussex in May 1969]. I read the data on the reverse of the card and was reminded I was 19 years old at the time of capture and added “swept adjacent to very rotten beech trunk” … 43 years later I’m trying to explain to myself why I did not investigate the beech trunk at the time, perhaps I forgot to take my hunting knife that day but re-visiting next spring with A.A. Allen we found the compartment had been clear-felled and replanted with a mix of Christmas trees and beech. There’s “good” habitat (old woodland) all around the area and the 5th British specimen was captured 3-4 miles to the east at Duncton Hill [in 1984].”
Confirmed records of E. cosnardi span the period from 6th May to 16th June whereas P. minutus adults occur in August and September. So it is possible, even likely, that a record from Peter Chandler of “a Platycis species” from the hedge south of Black Swan Lake, Dinton Pastures Country Park (Berkshire, VC 22) on 17th June 1993 relates to cosnardi, and likewise for a record from Dave Gibbs of a male P. minutus from Burledge Hill, ST5959 (North Somerset, VC 6) on 20th June 2002.