He can forget why he’s entered a room, struggles to get in his car, and sometimes is half a mile down the road before realising he’s left something vital in the house. At the age of 66, Sir Lenny Henry is starting to feel his age, so his new series – a reminder of his younger days on the stand-up comedy circuit – has come at just the right time.

In Legends Of Comedy, Sir Len meets some of Britain’s best-loved comedians to explore their work, get an insight into how their comedy brains function, and admit to their biggest mistakes – and he’s been longing to make it for years. 

‘Comedy is one of my favourite subjects,’ he says. ‘I’ve been doing it since I was 16 and I’ve always wanted to make a documentary about comedians but never had the chance to do it properly – until now.’

He starts by chatting to Paul Whitehouse, star of The Fast Show and Mortimer & Whitehouse: Gone Fishing who’s currently appearing as both Grandad and Uncle Albert in the stage version of Only Fools And Horses. 

While Paul has enjoyed huge success, Lenny draws a frank admission from him. Wondering why his friend Harry Enfield didn’t appear in The Fast Show, Paul reveals it was because Harry didn’t like some of the material, particularly the ‘Suit You’ sketches in which two salesmen would embarrass customers with a barrage of personal questions that would be deemed highly inappropriate today. 

‘I watch them now and go, ‘Hmm…’ admits Paul, looking embarrassed. ‘Could you do that today? Harry didn’t like them, and now I understand why my mum didn’t like them either!’

Later episodes in the series feature actress Sally Phillips, star of Smack The Pony and I’m Alan Partridge, stand-up comic and The Weakest Link host Romesh Ranganathan, and alternative comedy pioneer Alexei Sayle.

Lenny teases out frank revelations from all his interviewees, with Alexei admitting, ‘I didn’t take my acting career seriously enough – I did some awful garbage’, and Sally confessing that, ‘I was single when we did Smack The Pony and I would suggest certain men for certain roles just so I could meet them.’

Paul, who first met Bob Mortimer, his Gone Fishing sparring partner, in the days when he was best known as one half of comedy duo Vic And Bob, recalls, ‘He was a bit of a sad act who didn’t have any friends’, while Romesh winces as he watches his debut on TV show Live At The Apollo, and talks openly about failing in America and how he let himself down with Sky comedy The Reluctant Landlord. ‘If I’m brutally honest,’ he says, ‘I know I’d do it so much better now.’

Lenny says the programmes with Romesh and Alexei in particular might inspire him to return to stand-up after more than a decade away, in the hope he might be better at it. ‘Talking to Alexei and Romesh and seeing footage of them performing stand-up has definitely re-triggered an interest,’ he says. ‘It’s made me wonder how I would do it next time.

‘It’s just being grown up about it. There’s a type of comedian, like Simon Amstell for example, who talk about their family, their life, their mental health and their relationships. They aren’t afraid to say, ‘This is what the world is like for me.’ Since I wrote my book [his 2019 autobiography Who Am I, Again?] about my dad not being my birth dad, I could probably do that sort of stand-up.’

Lenny’s certainly very honest about the way old age is starting to affect him, and he sees no reason why that shouldn’t generate laughs. ‘People of my age deserve to make fun of ourselves – it’s how we survive,’ he says. ‘I do forget things, and I think that’s funny.

‘I hosted a show at the Royal Albert Hall recently celebrating the 50th anniversary of Philadelphia Records, and the whole audience was my age. It took them a long time to get back into the room after the interval – it was like herding cats – and they’d forgotten where they were sitting. If I do more stand-up, that’s the kind of thing I’ll talk about.

‘My mum used to watch me on TV and say, ‘That wasn’t very good but don’t worry, you’ll get better,’ adds Lenny. ‘She was right but it took a while – I had six years at the start of my career of not being very good at all!’

Now, at the age of 66, it might be worth another try.

Legends Of Comedy With Lenny Henry, Saturday, November 16, 8pm, Channel 4.