Lepiseodina rothschildi (previously Clogmia rothschildi, but also sometimes known as Telmatoscopus rothschildi)
This is one of 99 species of 'Psychodidae' found in the UK commonly going by a variety of names including 'Moth flies', 'Drain flies', 'Sink flies', 'Filter flies', 'Sewer flies'.
Given how very attractive some of these species are, as this photo demonstrates, I prefer the name, 'Owl midges'.
Many of these species are associated with drains, sewers and other sources of stagnant water, although this particular species is better known as a woodland inhabitant.
This association with stagnant water means they are often considered 'pests' particularly when in large numbers, but they are non-biting and harmless, unlike their close relations the 'Sand flies'.
Indeed I found this specimen and a few others, almost perfectly camouflaged on the trunk of a large tree (thank you headlamp) which combined with a length of just 2-4mm, makes them a very difficult find indeed.
Their fuzzy appearance is caused by a dense covering of long hairs on the body and wings, giving them a moth-like appearance.
Identifying Psychodidae is notoriously difficult without very close inspection of specimens.
Rothchildi is inseperable by sight from another species L. latipennis, but the latter is believed to be restricted to Italy.