Dani Garavelli: 50 years of Coronation Street

• The UK's oldest soap turns 50

The grim row of terraced houses is carved so deeply on the national psyche it is the only fictional location to feature on Google Street View. Sometimes it seems the only stumbling block to Scottish independence is the worry over whether Scots would still be able to tune in to the goings-on in Weatherfield.

So used are we to the Salford accents, so gripped by the loves and lives of ordinary people, it's difficult to conceive the soap was once considered too northern and dreary to capture the public imagination.

When the first episode was aired – on 9 December, 1960 – the executives who commissioned the initial seven-episode run thought it doomed. Yet the programme – which arrived in the same year as the gritty film Saturday Night and Sunday Morning – broke new ground and revolutionised TV.

Ordinary people – frustrated by the Received Pronounciation-dominated culture which failed to reflect the reality of their lives– were captivated by characters such as doughty Ena Sharples and flirtatious Elsie Tanner they could recognise from their own communities.

Within a few years, the soap was so popular that when one of its main characters, Martha Longhurst, was killed off (a heart attack in the snug of the Rovers Return during a farewell bash), shocked members of the public sent flowers to Granada TV. In 1981, more people tuned in to see Deirdre Langton marry Ken Barlow than watched the Royal Wedding two days later. And earlier this year the ashes of Frisky the Cat – who appeared in the title sequences of more than 1,000 episodes until his death ten years ago – sold for 844.

As the show gathered momentum, it accumulated high-profile devotees from across the social spectrum. Sir John Betjeman once declared: "When I watch it, I'm in heaven", while Camilla Parker Bowles was such a fan she agreed to wear a specially-commissioned brooch featuring the ducks from Hilda Ogden's "muriel" during a recent visit.

Now, as the programme prepares to mark its 50th anniversary in the time-honoured soap opera way (with a catastrophic tram crash) the BBC – which twice rejected the show – has produced a drama about how Tony Warren's idea finally came to fruition. Starring big names such as Jane Horrocks, Celia Imrie and Lynda Baron, The Road to Coronation Street looks at how the 23-year-old Warren got a drama originally conceived as Florizel Street on to the small screen.

The show will no doubt go some way to highlighting the Corrie's working-class roots, but how has this kitchen sink drama managed to sustain its popularity over five decades? What can explain its hold on the popular imagination? And to what extent does it reflect the dramatic way the UK has changed over half a century.

Until the 1960s, British television had been a haven of glamour and escapism. But in cinema and the theatre a change was already under way. In the late Fifties, John Osborne's play Look Back In Anger (made into a film in 1959) set the trend for a new kind of realism, while Room at the Top in the same year launched new obsession with the working classes.

But it was the play – A Taste Of Honey – written the year before, which prepared the ground for Coronation Street. It was written by teenager Shelagh Delaney, who said she was fed up with the way working-class characters were seen as peripheral to the main action, "quaintly doffing their caps" . Like the soap, it was set in Salford, written in the vernacular and centred on an adolescent girl, who abandoned by her sexually profligate mother, set out to find love for herself.

Like Delaney, Tony Warren wanted to produce a drama about "the Manchester I know, with dirt under its fingernails," and staged a sit-in in producer Harry Elton's office until he agreed to let him write it. For authenticity's sake, he insisted unknown actors with genuinely Northern accents be cast. From the beginning, he managed to capture the spirit of the ordinary people of city.

Using the characters of Sharples, Longhurst and Minnie Caldwell as a kind of Greek chorus, he demonstrated how even within the working classes there existed a hierarchy which separated the respectable from the morally degenerate (Tanner) and the downright common (in the shape of Stan and Hilda Ogden).

Noel Gallagher – who lobbied for a bit part – underlined how it provides acknowledgement for those outside London when one of the characters revealed he came from his hometown, Burnage. "That's the first time it's ever been mentioned on Coronation Street! I did a little lap around the coffee table."

Although, some critics have condemned characters such as Eddie Yates (hapless binman) and Les Battersby (feckless father of a family of delinquents) as stereotypes, the show's longevity lies in the way such figures are fleshed out and transformed into believable human beings.

Another key to its success has been the way it managed to move with the times without becoming relentlessly bleak. Over the years, and particularly since EastEnders and Brookside brought us Dirty Den handing Angie the divorce papers on Christmas Day and the rape of Sheila Grant (both 1986), it has been forced to introduce increasingly explosive plotlines in order to maintain viewing figures. Alan Bradley, a rapist and fraudster – who wooed Rita Fairclough before dying under the wheels of a tram in 1989 – was the first true villain to stalk the street, but several have followed: in 2003 Brian Capron won a clutch of awards for his portrayal of the serial killer, Richard Hillman.

But these have always been tempered with light relief. It is testament to the quality of writing in Corrie that comic storylines such as the one in which Ken Barlow tries to teach French to Raquel Wolstenholme ("A man once taught me how to say, 'It's a nice day, isn't it?'" she told Ken proudly. "'Voulez-vous coucher avec moi, ce soir?'") or the homophobic Battersby pretending to be gay in order to avoid eviction, have as a great a place in fans' affections than the big set-pieces.

Corrie has reflected major changes in social behaviour. For example, in the Sixties much of the social life of the street revolved around the Glad Tidings Mission Hall, but these days the only vocally religious characters are Emily Bishop and Sophie Webster – daughter of Sally and Kevin – and references to God are confined to weddings and funerals. Indeed, last year, the show was criticised as anti-Christian after Ken Barlow said he planned to tell grandson Simon "the truth" about religion, and producers covered up a cross in church where a wedding scene was being filmed.

It has, however, often been lauded for the way it tackles controversial issues. Since the late Eighties, it has sometimes seemed Britain's soaps were competing to confront the great taboos: homosexuality, Aids, teen pregnancies, abortion, assisted suicide, with the producers' desire to shock leading to contrived storylines.

Even more impressive has been its decision to introduce and stick with, transsexual character Haley Patterson has overcome the initial prejudices of both her boyfriend and the community at large. Haley first appeared in 1998 – six years before Nadia Almada blazed a trail in the Big Brother house. When she finally legally married Roy Cropper last week, her transsexuality was completely accepted.

"What soaps can do is show that different kinds of people that many of the viewers may not have come into contact with before are just part of every day life and then it becomes less about their difference and more about them taking part in the community and Coronation Street has sometimes achieved that," says Lesley Henderson, a former member of the Glasgow Media Group. "That happens when it's done well. Where there are problems is where characters come in and their problem is dealt with and then they leave, but I think the challenge is to manage to integrate people into everyday storylines."

So hugely has Haley impacted on the public's attitudes towards transsexuals, the official LGBT History Month website cites her as one of the important famous LGBT people in its history.

Despite its efforts, Corrie suffered in the ratings battle with EastEnders during the Nineties and early Noughties, however, by 2007, sensational new plotlines, such as Tracy Barlow murdering Charlie Stubbs, raised its viewing figures. Now it has average audience of more than ten million and is the second-longest running TV drama in the world after As The World Turns which began in the US in 1956 and ends this month.

Corrie's 50th anniversary will be marked with a live episode – which will see the survivors of the tram crash trying to deal with aftermath. Mystery surrounds the details but it seems certain the show will survive for, as the late Russell Harty once said: "There was life before Coronation Street, but it didn't amount to much."

Iconic episodes

ALAN BRADLEY FALLS UNDER A TRAM, 1989

PERHAPS the greatest villain in Coronation Street history, Alan Bradley made Kabin owner Rita Fairclough's life a misery in the late Eighties. Not only was Bradley, the estranged father of Jenny, a girl Rita was fostering, involved in a bust-up in The Rovers with Terry Duckworth, he tried to pull the barmaid Gloria Todd and raped his employee Dawn Prescott.

Then, in order to fund his new business, he remortgaged Rita's house, attempting to murder her when she discovered the extent of his dirty dealings.

The episode in which Bradley finally met his death under the wheels of a Blackpool tram was watched by 26.9 million people - the largest audience in the soap's history.

THE JILTING OF LEONARD SWINDLEY, 1964

EMILY Nugent was already wearing her wedding dress when she decided she could not go through with her marriage to Leonard Swindley, a devout Christian and manager of the Glad Tidings Mission Hall. Afraid of being left on the shelf, she had proposed to her putative groom, but right up to the moment they were supposed to exchange their vows they continued to call each other by their surnames. When Emily finally broke the news, Leonard was courteous, worrying as much about the shame she must be experiencing as his own hurt feelings.

RICHARD HILLMAN CONFESSES, 2003

These days, every soap boasts a serial killer, and on Coronation Street that was Richard Hillman. He took out three characters - including hairdresser Maxine Peacock - before his new wife Gail realised what was going on and confronted him. In a tense scene, Richard broke down and confessed before leaving. This is the episode that gave us the famous quote: "You're Norman Bates with a brief case."

RAQUEL COMES BACK TO SEE CURLY, 2000

The poignant relationship between Curly and Raquel Watts provided Coronation Street with some of its most tender (and most amusing) episodes. There was scarcely a dry eye when Raquel - who left Curly for a beautician's job abroad came back to see him at 2am on the turn of the millennium - not to win him back but to ask for a divorce so she could marry a French vineyard owner. While there, she told him she had given birth to their daughter, Alice.

• The Road to Coronation Street will be shown on BBC4 on Thursday at 9pm