The pair have remained close friends, but Briers said his other principal co-star Felicity Kendal, 66, who played his wife in the Seventies hit The Good Life, had “disappeared” from his life.

“I’ve got emphysema, you see, so I’m b*****d,” he told the Daily Mail.

“Five hundred thousand cigarettes, darling — that’s the trouble.

“I haven’t even got the strength to garden any more.”

He added: “It’s totally my fault. So, I get very breathless, which is a pain in the backside.

“Trying to get upstairs, oh God, it’s ridiculous. Of course, when you’re bloody nearly 80 it’s depressing because you’ve had it anyway.

"The ciggies got me. I stopped ten years ago but too late. If you do it in your thirties then you’re OK, but after 30 it gets you.

“I was diagnosed five years ago and didn’t think it would go quite as badly as it has. It’s a b*****, but there it is. I used to love smoking.”

In The Good Life, Mr Briers played Tom Good, a suburban husband who gives up his job and leads a self-sufficient lifestyle by growing his own food in his garden.

The show’s comedy was centred on his bickering relationship with Barbara, his wife played by Miss Kendal. He later disclosed the pair had never been close in real life and have since lost contact with each other.

His varied career saw him narrating the 1970s children's cartoon series Roobarb And Custard, as well as adding his voice to the animated version of Watership Down.

Sir Kenneth spoke fondly as he paid tribute to Briers today. saying: "He was a national treasure, a great actor and a wonderful man. He was greatly loved and he will be deeply missed."

They worked together on Henry V, Peter's Friends, Much Ado About Nothing and Mary Shelley's Frankenstein during their lengthy association.

Briers, who trained at Rada, made his West End debut in the late 1950s in Gilt And Gingerbread, and went on to work on a number of British films - Bottoms Up, Murder She Said, The Girl On The Boat and Fathom, alongside Raquel Welch.

His most recent performances have included roles in last year's Cockneys Versus Zombies, plus a small role in a newly released movie version of stage farce Run For Your Wife.

Peter Egan, his co-star in Ever Decreasing Circles, said: "I spent nearly 10 years just laughing. He was just the most magical comedian, a huge talent, has been a part of the nation's lives for over 50 years."

Speaking to Radio Berkshire, Egan went on: "He is a centre-piece of our humorous culture and a magnificently talented man. I'm so deeply sad today that he has left us. He was a great person."

His godson, the actor and director Samuel West - whose mother Prunella Scales appeared alongside Briers in Marriage Lines - said on Twitter: "What a lot of joy he spread."