About 15mm long.
The plant, I think, was water-mint.
No interactions present.
What makes it Tansy beetle and not mint beetle? ie Chrysolina graminis rather than C herbacea. C graminis appears to be rarer than C herbacea, and they look very similar and both feed on mint.
Lat/Lng: 51.4, -1.1
OS grid ref: SU6571