I think I've got this right as Oedemera lurida. The back colour seems to vary a little, or the pictures are not showing it correctly. The colour on my pics was as it looks.
http://popgen.unimaas.nl/~jlindsey/commanster/Insects/Beetles/SpBeetles/Oedemera.lurida.html
It's food is mentioned as being Geranium sylvaticum, the plant it was feeding on is probably a hybrid of that as it's a self set from a plant I got from a neighbour.
The top of the abdomen on mine is orange with grey under, I found this pic which just shows that.
http://www.zin.ru/Animalia/Coleoptera/eng/oedlurdg.htm
More
http://www.koleopterologie.de/gallery/FHL08/oedemera-lurida-foto-erezuma.html
http://www.koleopterologie.de/gallery/FHL08/oedemera-lurida2-foto-weisenboehler.html
http://www.koleopterologie.de/gallery/FHL08/oedemera-lurida-foto-lenz.html
The next pic is named as Oedemera lurida and looks vey similar in colour to mine, location Peterborough is quite close to me.
http://thenaturalstone.blogspot.com/2004/05/froghopper-and-beetle.html
The female of Oedemera nobilis is green and doesn't have the very inflated thighs of the male,
http://www.koleopterologie.de/gallery/FHL08/oedemera-nobilis-female-foto-weisenboehler.html
I can't see the orange on it though in this pic
http://www.koleopterologie.de/gallery/FHL08/oedemera-nobilis-foto-koehler.html
There are many on this site
http://www.koleopterologie.de/gallery/FHL08/fhl08.html#oedemeridae
