As if completing the world’s toughest triathlon last year was not enough, superfit Paul Parrish has let himself in for another major challenge which started on BBC2 this week.

Paul, who lives in Wheathampstead, is taking part in Special Forces: Ultimate Hell Week, a new six-part series presented by cricketer Freddie Flintoff in which some of the fittest men and women in the country face the toughest challenges of their life.

Sunday’s first episode showed the recruits taking on gruelling selection tests devised by US Navy SEALS which, unsurprisingly, involved spending time in freezing cold water both at base camp and on a beach in Wales.

But former journalist Paul, who is now director of fundraising and marketing for the charity Aspire, survived the first programme - although around half a dozen of his colleagues caved in - and in the next few weeks will be seen undergoing selection tests used by the likes of the Philippine’s NAVSOG, the Russian Spetsnaz and the UK’s SAS.

The aim of the programme is to push the physical and mental endurance of the participants to the limit - but that is something to which Paul, who was formerly director of fundraising at St Albans hospice Grove House, is no stranger.

Last year, at the age of 49, he completed the Arch to Arc Challenge - regarded as the world’s hardest triathlon - becoming only the 20th person to complete it since it began in 2001.

It started with an 87-mile run from Marble Arch to Dover followed by a solo swim of the English Channel and cycling the 180 miles to the Arc de Triomphe.

Not only did he raise thousands of pounds for Aspire but he finished the challenge with the sixth fastest overall time of 84 hours 44 minutes.

Paul said he understood there had been thousands of applicants wanting to take part in Special Forces: Ultimate Hell Week but he was successful in getting into the final 29 of what he described as ‘this rather brutal show’ despite being older than many of the other participants.

The programme can be seen at 9pm on Monday nights on BBC2.