A yellow soldier beetle, probably Cantharis decipiens (Coleoptera: Cantharidae). Recognizable by the pattern of black and yellow on the pronotum (the plate just behind the head).
Compare with the similar Rhagonycha lignosa. There are several keys to UK soldier beetles available out on the web: here, here and here, for example.
Photos taken in Whiteknights Park, Reading University grounds, Reading, UK, on 2012-04-27.
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