Tachinid Fly

Tachinid fly Mintho rufiventris (Diptera: Tachinidae).  This species is very similar to Eriothrix rufomaculata (they both have reddish patches on the sides of the abdomen) but M. rufiventris has two longitudinal black stripes on its upper thorax, both broad, while E. rufomaculata has four black stripes: two broad and two narrow (see here for more differences).

This is a side view of M. rufiventris:

Photos taken in Whiteknights Park, Reading University grounds, Reading, UK, on 2010-09-21.