Confidence: It's likely to be this, but I can't be certain.
Notes: Using the capital 'E' on the base of the plastic tub in the 2nd pic as a scale, which is 3.5mm long, the forewing length on this caddis is very close to 13/14mm(its close to 4x the length of the letter E). Too big for P. brevis. Conspersa and geniculata are similar in size but this potential ID of conspersa is based on the strength of the dark wing markings as shown in Barnard and Ross and indeed their similarity with the above. Found at rest by a moorland stream, Greenhalgh and Ovenden 2007 suggests P. conspersa is an upland species but geniculata might also be? If conspersa and geniculata cannot be reliably seperated from an image like this please feel free to revise the identification.