On The Two Ronnies' 50th birthday, we reveal what made the Saturday night show a national institution

Their packed programme of colourful comedy came to be synonymous with Saturday nights on BBC One (though it did flirt with Thursdays and BBC Two for a few series). When I hear the big-band, "you're in for a good time" theme tune by Ronnie Hazlehurst now, it brings back a flood of happy memories: two suited gentlemen sitting behind a desk to open the show; a few snappy two-handers founded on a quickly established theme; Barker punching out a monologue with breathtaking precision; the occasional "Ladies and gentlemen, Miss Barbara Dickson"; an arm-chaired Corbett with his Olympian digressions; an all-singing, sometimes-dancing finale; and of course a few late items of news.

The Two Ronnies ran for 12 series and 93 episodes between April 1971 and December 1987, drew audiences of up to 18.5 million, and regularly appeared on the cover of Radio Times – from day one onwards.

We all have a favourite sketch – be it the immortal Fork Handles (secretly written by Barker), the ingenious Mastermind spoof, Answering the Question before Last, Sweet Shop or perhaps Racing Duck – a serial, such as The Phantom Raspberry Blower of Old London Town, written by Spike Milligan "and a gentleman" (Barker again) – and a musical finale.

The Two Ronnies was where you went to stock up on jokes. "Coming next, Googie Withers and what to do if it does" still tickles me to this day. And to ensure a constant supply of top-drawer gags, the show employed an army of writers, including David "Reggie Perrin" Nobbs, Barry Cryer, assorted Pythons, Goodies and Barker himself – usually under the pseudonym Gerald Wiley.

"Through the late '70s and early '80s, writing for The Two Ronnies was the pinnacle of my own career," says David Renwick, who wrote for more than half the episodes and went on to create big-hitters One Foot in the Grave, Jonathan Creek and the acclaimed Love Soup.

"It wasn’t just that they were so popular, the BBC’s flagship entertainment series on a Saturday night, but there was a gloss and perfection about everything they did that inspired reverence in every quarter. Mike Yarwood once said to me it didn’t matter how good or bad the sketch was, he just loved watching them work because their performances were so classy."

Renwick first began sending in jokes for "the news desk" in 1974 but he describes the show as a tough nut to crack. Submissions would be sent in from all over the country, then script editor Peter Vincent would whittle them down to about 100.

"The two Rons would then read all of them, without comparing notes, and tick the ones they liked, and only those with two ticks would get through. Even then, a joke that seemed to falter at the dress run would frequently get the chop, so the chance of success was not high. But somehow I managed to get a commission from the then-producer Terry Hughes to come up with two minutes a week, and that’s where my association with the series began.

"I made a point of attending all the dress rehearsals and recordings, just to get my face known. I watched and studied the way the two of them worked, and observed the meticulous authority that Ronnie B clearly wielded over every aspect of the production. It was all conducted in a very congenial way but with that quietly clipped precision that ultimately brooked no argument. And Ronnie C, of course, trusted his judgement to the hilt."

Someone else who enjoyed working with them was April Walker, who appeared in 15 episodes from 1973 onwards. "It was enormous fun," she tells RadioTimes.com. "It was a joy to go to rehearsal, which was something that I really looked forward to every time I did it, because there never seemed to be a cross word between the two of them. If they had any difference they discussed it, analysed the situation and came to a conclusion together. The atmosphere was always lovely."

In her long career, Walker has worked with many of the comedy greats from Kenny Everett to Eric Sykes and been in classic shows like Fawlty Towers, Dad's Amy and The Onedin Line. But did she get the giggles while working with the Rons? "Oh yes, definitely. It was always difficult to keep a straight face!" And what about her favourite sketch? "I suppose the morris dancing sequence. That was fun. It was the finale and we all had to sing the songs and the words were so lovely…"

It was the end-of-show spectaculars that most appealed to Don Smith, 88, who photographed the stars on many occasions. "As a part-time musician myself, it always astonished me that they were singing new words to old songs and there was never a moment’s hesitation. I never noticed any mistakes ever and I just admired them so much. They were just so professional."

"One of the geniuses of their show was Ronnie Hazlehurst, the musical director. I think of things like the marching sequence with a brass band. It was done with such meticulous accuracy. Unbelievable."

Renwick agrees: "It amazed me how flawlessly they managed to pull off such a truly packed programme every week. While all the songs and monologues would be safely on autocue, the rest of it had to be learnt, usually in the space of just a few days. Yet they rarely fluffed a line. And the seemingly bottomless well of characterisations and voices that Ronnie B, in particular, was able to conjure up was a joy to behold.

"I saw him corpse only once in the space of 12 years, during the run-through of David Nobbs’s Complete Rook sketch, where his weary, disgruntled waiter was a masterly exercise in understatement."

The Two Ronnies was recorded at BBC Television Centre, used for major dramas like I Claudius, the BBC Shakespeares and sometimes operas, as well as big comedy shows including Morecambe and Wise.

"We had a live audience and that made a huge difference because one really got the buzz," says April Walker, "and for all of us who love doing theatre anyway, it’s always the audience who make it.

"If things went wrong then, if Ronnie Corbett wasn’t available – if he was in make-up being changed into some other character – the actual warm-up man would go on and say, ‘Now listen, I want you to understand that you have not heard these jokes before and you will laugh even more next time', and sure enough the audience always played their part. What a happy time it was. It was wonderful.”

Another hugely popular element of the show was Corbett’s skilfully digressive anecdotes, many of which involved his producer. They were enjoyed by writer David Renwick, too: "Those chair spots, originally devised and scripted by Spike Mullins, had always been a highlight of the show for me, so when Spike ran out of steam in 1978 and I was invited to take over, it was a real labour of love.

"Ron and I would confer about the choice of an old shaggy dog tale each week, sometimes he’d send me books of after dinner stories or relate a joke he’d heard at the golf club, and I would then use this as a backbone for that week’s meandering monologue."

One of the jewels in the Two Ronnies crown was, of course, the 1980 Mastermind sketch, with an impressive 20 laughs in under three minutes. But its path to our screens was anything but smooth, as Renwick explains: "You couldn’t always tell what was going to appeal to them. In 1980 I reworked an old sketch I’d written for The Burkiss Way on radio, with all the questions and answers on Mastermind slipped out of sequence. When I read it back I literally tore up the pages because it felt too contrived.

"The next day, as desperation set in, I rescued the pieces and decided to try my luck. On the night, they were originally planning to record the sketch twice, so that by the second pass the audience would get all the connections. Surprisingly, the whole thing went like a bomb the first time, and Ronnie B just got up from the desk and muttered to the producer: “We’re not going to do that again.”

Clarifying one technicality, Renwick says. "I was always aware that Ronnie Corbett's response to the question 'What do people kneel on in church?' – 'The Right Reverend Robert Runcie' – was the incorrect term for an archbishop, and should have been 'The Most Reverend'. But the comic alliteration won out, and after all these years no one has ever pulled me up on it!"

But if fans have a favourite sketch, so do the writers. Eric Idle, who like many other Ronnie writers had worked on The Frost Report in the 1960s, told us, "My favourite was a sketch about two couples meeting at a party and thinking they know each other, so they're both fishing desperately: 'This is er... my wife and this of course is... er... his wife.'"

For Renwick the funniest was the 1983 squash sketch written by Colin Bostock-Smith, "which is character comedy at its finest. The two men have just returned to their changing room after a gruelling session on the court – Ronnie C, all flushed and perspiring, and Ronnie B, still fresh as a daisy, in his 'ruddy Burton’s suit', trying to work out which of them won the match. Corbett’s apoplectic reactions are a tour de force. Barker asks, 'How many goals did I get?' and apologises for holding his 'bat' at the wrong end. 'It’s not a bat,' says Corbett – 'THIS – is a BLASTED RACKET!'"

Another high-profile Renwick skit was Crossed Lines (1981), in which two men on adjacent public telephones effectively answer each others' sentences.

Very often the comedy set-ups that were teased but never materialised could be just as funny. Some would almost invite the audience to second-guess the punchline. For instance, "The next sketch is about two workers caught in an explosion in a ball-bearing factory. In it, I play a man who loses his bearings..."

The double act's fizzing, quickfire chemistry is legendary, as was their knack for nailing a one-liner. But what were the Ronnies like as people?

"They were just a delight," says April Walker. "Funnily enough it was usually Ronnie Corbett who was warm-up guy for the show and he would go on in front of the audience and tell jokes and get everybody started up, then he would introduce the rest of the cast. He was very good at doing off-the-cuff chat. Ronnie Barker was delightful and loved talking to the audience but the one who actually told the jokes was Ronnie Corbett."

Renwick confirms that they were quite different personalities, united by a single comic vision. "Ronnie Barker was a highly versatile actor, with the magic ability to make people laugh. Corbett was at root a Vaudevillian, able to exploit his size and very physical skills to great effect, who then turned his talents to acting. Barker, rather like Peter Sellers and Alec Guinness, could transform himself into almost any character, while Corbett remained essentially himself, investing every role with the same recognisable twinkle.

"Ronnie B never saw himself as an especially funny individual, and was only really comfortable on screen if he could hide behind a characterisation of some kind, even if that involved nothing more than a moustache, as one of those stern-faced announcers at the desk. He loved the way Ronnie C could just walk out on stage with a microphone, completely comfortable in his own skin, and make an audience laugh for an hour. It was something that was quite beyond him.

"The odd thing was that, in private, Ronnie Corbett was by far the more serious of the two. Barker, in conversation, was instinctively frivolous, reaching for the nearest one-liner or piece of wordplay – he used to refer to my wife Ellie as “Light Entertainment”: LE, as it was known in the trade. But Corbett was more often studious and thoughtful, and never short of a colourfully literate turn of phrase."

April Walker remembers Barker writing a sketch with her in mind, about a village called Mile Away, which was filmed in Gloucestershire. "Because we were there for some time filming I got to know Patrick Troughton – who played a local yokel – and the Ronnies, in a social and chatty way and not just before a recording.

"Afterwards I asked Ronnie Barker whether it would be at all possible to have a recording because I had failed to record it and he sent me a videotape of it. He addressed it: 'Starring Miss April Walker with…' and then in tiny letters underneath 'Ronnie Corbett and Ronnie Barker'. It was just so enchanting. I’ve still got it here. I have nothing but happy memories of being with them. They were a joy, both of them."

Of the seaside-postcard nature of some of the show's humour, April says the scripts could be risqué, "but it was all double entendres. It was all good clean fun."

Renwick adds, "Political correctness, of course, was still in its infancy then... Since The Two Ronnies left our screens, comedy styles have evolved dramatically. Much of their sustained appeal, I think, can be filed in the category of nostalgia. It’s fair to say a lot of that material today would not survive executive scrutiny. Very few successful shows from the '70s and '80s, in fact, could now be screened without extensive cuts, or announcers warning viewers about their potential for offence. They survive thanks to their context in a bygone age.

"The Two Ronnies of course shared a common ancestry with the Pythons, in the Frost Report and the satire shows of the '60s. And as they extended their appeal to a more mainstream audience they were careful always to keep an element of that clever, quirkier style in the mix. At a time when audiences would still gather round the set as a family this would have ensured there was something for everybody, every week.

"Anything that smacked of Benny Hill was starting to become unfashionable within the television industry and the new generation of performers."

Renwick refers to a savage parody of The Two Ronnies by the coexistent Not the Nine O'Clock News, "which I know had deeply offended Ronnie B, and I’m not surprised. But Not the Nine O’Clock News was then 'hip' and on the ascendant, and just as people like Mike Yarwood were now suffering next to Spitting Image, the Ronnies were in danger of looking old-fashioned.

"It’s probably right that it finished when it did, before its more traditional style of humour came to seem passé. Whatever the cultural shifts since then, their genius and longevity as supremely talented professionals can’t be denied."

So it was goodnight from both of the Ronnies, though repeats continued to be well received, and of course Barker and Corbett had other successful solo projects on the go, such as Open All Hours and Sorry!.

But the pair's professionalism shone through all their years of working together. "The Ronnies knew exactly how to time and temper their delivery so as to get the laughs without straying into pantomime," says Renwick. "Ultimately it’s all to do with rhythm. Get the wrong stress on a syllable and you lose the laugh. But in all of this they were masters of their craft."

The writer remembers long after the shows had finished, Ronnie Barker and his wife Joy would throw summer parties at their home in the Cotswolds, with a band playing Dixieland jazz and waiters circulating with champagne. "The year after his death [in 2005] Joy generously threw another summer party for old times’ sake, and Ronnie Corbett’s voice fell away in swallowed tears as he stood up and proposed a toast for his former partner. It was a terribly, deeply moving moment for everyone there."

And when Ronnie C died in 2016, Radio Times gave him one final front-page send-off, with a Corbett quote that reminded fans of the two Ronnies' calm, no-dramas rapport: "We never had a cross word. He did a lot more worrying than me because he wrote more. I never minded him being in charge. I knew I was in safe hands and he had excellent judgement."

The Two Ronnies Sketchbook, containing many of the pair's best-loved routines, is available on BritBox – check out our full TV Guide for more recommendations.

The Radio Times Easter issue is out now.