Emerged from the caterpillar illustrated at http://www.ispot.org.uk/node/119386
No interactions present.
Mark Shaw is a great expert on these things, I'm happy to go with what he says.
And his generosity in identifying things on behalf of complete amateurs like me is greatly appreciated.
Lat/Lng: 51.540316447216, -0.32921433448792
OS grid ref: TQ159837