John Alford, a 54-year-old former television actor known for his roles in British series Grange Hill and London's Burning, has died while serving a prison sentence at HMP Bure in Norfolk.

Prison staff found Alford unresponsive in his cell on Friday when they opened his door, according to reports. The circumstances surrounding his death have not been disclosed.

Alford had recently been sentenced to prison for sexual offenses involving two young girls. The actor had been serving his sentence at the Category C prison facility in Norfolk at the time of his death.

The actor was best known for his television work in the 1980s and 1990s, appearing in the long-running children's drama Grange Hill and later in the firefighter series London's Burning, which made him a recognizable face on British television.

A prison service investigation into the death would be standard procedure, though no details about the cause of death or ongoing investigations have been released by authorities.