Another picture from Cromhall

I was concentrating on the sawfly at the time, but I think it is the fly that draws the eye in this photograph. I don't think I realised how attractive it was at the time - it's just a fly after all.

I think the sawfly is a species of Athalia (see comment). At one point it would have been easy to identify it as A. rosae, but it appears that there may have been some revisions to the genus. My best guess is that this common Athalia is now known as A. circularis, but it's not clear as my books don't adequately cover sawflies and most of the internet sources evidently haven't caught up. Perhaps someone can tell me?