This is a small caterpiller on saw-wort, it has some spiky hairs perhaps an expert can help with the ID
No interactions present.
Compare with http://ispot.org.uk/node/17799
Agree it looks like a pug. No pugs are listed as specialising on Saw-wort,so presumably it is one of the species that feeds on a variety of plants.
Entomologist and biological recorder
Any idea as to the species, or is more information needed
Lat/Lng: 52.2, -3.4
OS grid ref: SO0560