There are about 65 species of Longhorn Beetle that have been recorded in Great Britain, many of which are rare and hardly seen. So about 20 species should be found in Glamorgan. Here's the ones I've managed to photograph in the valley.
Grammoptera ruficornis - one of the smallest and commonest Longhorns
Rutpela maculata - elytra colour variation 1
Rutpela maculata - elytra colour variation 2
Stictoleptura rubra - female with orange thorax
Stictoleptura rubra - male with black thorax
A further 3 species have been recorded in the valley before I had a camera, they are -