Stroud actor Keith Allen stars as the Bullseye Murderer in an ITV drama tonight, based on the true story of a serial killer who appeared on a gameshow while on the run.

The Pembrokeshire Murders, which airs its second of three episodes at 9pm, casts Mr Allen, from Minchinhampton, as John Cooper, who committed two separate double killings in the 80s.

The killer shot siblings Richard and Helen Thomas in their home in Wales in 1985, before murdering hikers Peter and Gwenda Dixon four years later in Pembrokeshire - exactly one month after he had appeared on the ITV gameshow Bullseye.

The murders remained unsolved until 2006, when detective superintendent Steve Wilkins reopened the cases and applied emerging forensic investigation methods to it.

Combined with footage of the Bullseye show and a police sketch, the investigators had their man.

John Cooper was arrested for murder in 2009, and sentenced to life imprisonment in 2011.

All his attempts to appeal the verdict were unsuccessful.

Keith Allen, known for Shallow Grave (1994), the Others (2001) and Robin Hood (2006), will be joined by Luke Evans who plays Welsh detective Steve Wilkins, tasked with tracking down the twisted criminal.

Allen has also appeared in Trainspotting, Eddie the Eagle and Kingsman: The Golden Circle, and is father to singer Lily Allen and Game of Thrones’ Alfie Allen.

The show, rated 8.2 on IMDB, will air on ITV or you can stream it live via the ITV Hub, which also features the first episode if you need to catch up.

The final episode will be showing tomorrow, Wednesday 13.