A pale brown caterpillar, about as long as my little finger but not as thick, on rushy grass.
No interactions present.
Thank you David, it does look like one of the xestias.
I didn't think anyone would identify it after all this time - good old ispot!
I've been flicking through old records without IDs using the maps feature. Quite a lot that we un-identified, especially in the early days.
Lat/Lng: 50.6, -2.1
OS grid ref: SY9680