I initially found this large cranefly on top of blanketweed in my garden pond. They can grow up to a length of 2cm (3/4 inch), and have a distinguishing pale line which runs down the back of the abdomen. This is a female with the pointed abdomen, which is actually her ovipositor for laying eggs.
The adults can be seen March to October, and around water. Common and widespread throughout. The semi aquatic larva feeds on rotting plants at the bottom of ponds or streams.
August 2017, Staffordshire, England.