Difficult to identify, females can be indistinguishable. Male anal tube (final abdominal segment) is long in M. attenuata, nearly as long as the rest of the abdomen. It has a dark spot on the clavus and other dark marks on forewing.  Dissection of male will confirm identification

Mocydia crocea has more pointed wing apices.  Mocydiopsis parvicauda is very similar, and may also have a dark spot on clavus

males

Dissection of adult male required to confirm species. 

To follow.

Adult: July to October

Common (ref. UK Auchenorrhyncha checklist 2021, on British Bugs website)

There are few records from Leicestershire and Rutland, probably due to identification difficulties. 

https://www.britishbugs.org.uk/homoptera/Cicadellidae/Mocydiopsis_attenuata.html