(This is a context shot showing location of spider on Bull Thistle)

Looked at Yellow Sac Spider but the multiple green-speckled bands seemed inconsistent with specimens I saw, and could not find another spider closer (although my knowledge is limited!).

Appears to have been feeding on a Common Red Soldier Beetle (Rhagonycha fulva), just under the crown of a Bull Thistle (Cirsium vulgare). I will add one shot of it from slightly different angle, and one context shot of the top of the bull thistle.