Central Trains Class 156 DMU at Cheltenham Spa, UK
These units were formerly known as Super-Sprinters under BR, and were specified for medium-distance fast and semi-fast services (Regional Expresses). They have a 75mph top speed (about 120km/h), and have 2+2 seating throughout, with a mixture of airline and table seating. They were initially used to replace Class 150 services on some routes, which were not suitable trains for longer distances, with their 3+2 suburban-style seating and layout.
This is the Birmingham to Cardiff semi-fast service - which will gain increasing importance as this will become the only regular link between Cardiff, Gloucester, Birmingham and the North, since Virgin is all but ceasing services to Cardiff and Gloucester. As of the timetable change (28 Sept 03), however Class 156s will no longer run this route, as the Strategic Rail Authority has ordered that much faster, air-conditioned, Class 170 (100mph / 160km/h) units should be used.

Photo by Timothy Vince (le_random@yahoo.co.uk)