He plays the grandson of Ronnie Barker’s character Fletch in the show.
Forty years after Norman Stanley Fletcher served his time at Slade Prison, Nigel Norman Fletcher – also nicknamed Fletch – is banged up in Wakeley for cyber crimes.
Kevin, 37, said: “I was unsure and I was very nervous and I still am. I think it’s something that people hold very close to their hearts.
“I was slightly reticent to jump on board at first because I thought, ‘If it isn’t good, as an audience member, I would completely slate it’. “
“It’s big shoes to fill. It’s Ronnie Barker and it’s my favourite sitcom of all time.”
Kevin admitted: “Throughout the rehearsal process of the pilot I was never sure if it was going to be a success or not.”
But he added: “We’ve pulled it off, I think.”
The first episode, which will be broadcast this week, sees Fletch caught up in a love triangle when he writes romantic letters for lovelorn fellow lags.
Kevin says he has adopted many of the mannerisms employed by Barker as Fletch to establish the Fletcher family connection.
“I noticed in my children that they’ve got certain mannerisms that their granddads had or an uncle or an aunt. It’s in their DNA and you notice that. That’s how I wanted it to feel. I wanted it to feel familiar but not an impersonation.
“What I wanted to achieve from this was if Ronnie Barker watched it he would think it was done well.”
There are many echoes from the original series.
Catastrophe’s Mark Bonnar plays ferocious Scottish prison officer Meekie, in a nod to Mackay (Fulton Mackay) from the original.
Fletch’s cellmate Joe Lotterby, played by EastEnder Dave Hill, served time with Fletch Snr.
The BBC One series is written by the original writers Dick Clement and Ian La Frenais.
A pilot episode was televised last year.
Porridge, Friday, 9.30pm, BBC One.