This sawfly found its way into our kitchen window, so I was able to get some decent photos, but I’m still unable to get to an identification. There are 500 species of sawfly in UK, and they are very much under-represented on the Web, despite many being quite large and well marked. Changes of the classification also make it harder to find references - but a good site is https://www.sawflies.org.uk, which shows a few examples from this Genus, Euura. This individual had a nice pastel green colour on the sides of it’s body and the wing spot (pterostigma), with a striped abdomen which in the middle part was translucent against the light. These sawflies are mostly associated with trees, such as willow, hazel and alder. Hopefully I’ll be able to get closer to an identification at some stage.