large species found in moth trap.
No interactions present.
L. marmoratus was the other that I planned to suggest (having seen pictures of it before, I may have photographed it before) but the only illustration I had in reference material of that species showed a caddis with very faint markings. It put me off as the above fly is so well marked. I was going just by appearances alone.
There is a new ID guide shortly to be publshed - AIDGAP series, I think - which will help a lot, because current literature does have its limitations. I use the FBA key, backed up by the old monograph by Mosely: both have wing pattern photos but in black & white and not covering all species.
They are a tricky bunch, hopefully this new volume recommended by Inopinatus below will help ID these insects. It sounds good, looks good too.
I think that this probably is marmoratus - there are other possibilities within the Limnpehilus genus such as rhombicus although marmoratus usually has bolder markings as shown here. The much anticipated new guide has been published and can be found here http://www.field-studies-council.org/publications/pubs/the-adult-trichoptera-(caddisflies)-of-britain-and-ireland.aspx
Thanks for posting this link Inopinatus. Should be good.
Lat/Lng: 49.4812, -2.5423
OS grid ref: S^608535