A small (1.5 to 2 mm) black weevil.  The larvae of this species usually mine Hawthorn leaves, but also other members of the Rosaceae family. The mines are usually small upper surface blotches, but later in the year on hawthorn the mines may be larger - like a broad gallery or blotch - wth dispersed frass.  In this form they can look like a moth leafmine, but have a squat bright yellow larva, with a black head.

Adult mine

Adult: Unless identified by a recognised expert, photographic evidence is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used. Note the beetle's size and describe the identifying characters. It is advisable to retain the specimen in case further checks are needed.  Mine: provide good backlit photographs that show the larva inside the mine. 

Hawthorn and related plants

Rhamphus oxyacanthae leafmines are most likely to be encountered in autumn.

Widespread in England and Wales, but sometimes local in distribution.

Occasional in Leicestershire and Rutland.

http://www.leafmines.co.uk/html/Coleoptera/r.oxyacanthae.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/coleoptera/polyphaga/cucujiformia/curculionoidea/curculionidae/curculioninae/rhamphinini/rhamphus/rhamphus-oxyacanthae/