Is this a Sheild Bug?

yes HB it's a shield bug, but to be honest the damage they do in my garden is very small so i leave them be, they suck sap late summer / autumn on runner beans and a few other plants..

Glad to see this on here and to know it's not a real threat. I find them every so often and didn't have a clue what they were.

The green shield bug is common throughout England and Wales, but less so in Scotland. In spring and summer it is bright green and stippled with tiny black dots, then changes to greeny-bronze in autumn, it has dark brown wing tips.
It is also called a green stink bug as it produces a pungent odour from special glands if handled or disturbed. I agree with Surreylad as I never see more than 1or2 so the damage cannot be great?