Physatocheila dumetorum

A small brown lacebug, 2.5-3mm, with down-turned sides to the pronotum.  There are three keels on the pronotum, all reaching the head.  It is wider across the middle of the forewings, and has a dark head and dark mark across the wdest part of the forewings.  

[note: according to British Bugs website (link below), it is debatable whether the very similar P confinis is a separate species] 

Physatocheila confinis 

Detailed examination of the specimen is needed to identify the species.

Typically found on lichen covered trees, particularly hawthorn.

Adult: All year.

Fairly frequent across much of England and Wales.

Status in Leicestershire and Rutland not known.

https://www.britishbugs.org.uk/heteroptera/Tingidae/Physatocheila_dumetorum.html