Seen on a rose bush. About 0.8cm long
No interactions present.
Having seen the information on the RHS site about the rose sawfly I took a look at the rose stem where the insect had remained calmly for a long time while I took its photo. Just as described, there was a long slit where it had laid its eggs!
I had hoped that this was a type of hoverfly which was going to eat the aphids on the rose but it looks as though it's yet another pest to contend with!
Lat/Lng: 51.5, -2.5
OS grid ref: ST6781