5mm long leaf eater, larger head end, eating wild service tree leaf.
No interactions present.
Possibly Caliroa sp.
Thanks for the general group. This helped me pin it down to a larva of one of these flies. Caliroa cerasi looks a likely candidate.
Liz and Tim
Sawflies are actually wasps, not flies...
Lat/Lng: 50.9158, -3.5574
OS grid ref: SS906140