This is not the common name of this large shield bug, Pentatoma rufipes, which actually goes by Forest or Red-legged Shieldbug, but it should be. I found the individual above todaty on a pavement today and had a plastic pot at hand to bring it home and give it the white bowl treatment to bring out its colours. This shiny, metallic beauty becomes an adult at the end of June or July, as the photo below of a teneral adult, just moulted out of its also shiny last instar nymph skin shows. Even when the full colours are not evident, the prominent 'shoulders' are characteristic.
Teneral Forest Bug
Large shieldbugs are relatively easy to identify, even at their nymphal stages. The British Bugs site is always good starting point.