DUM-de-dum de-dum-de-dum, dum-de-dum de-dum-dum . . . Whether a lapsed listener, dedicated fan or someone who has never tuned in once everyone has heard of the Archers and a village called Ambridge.

It is part of our institution. As English as cricket, cream teas, Sunday roast and village greens. Next year the world's longest running soap celebrates fifty years of broadcasting — and it looks like there's plenty of life in the old dog yet.

If you want to get a breath of Ambridge, meet some of the characters and gain some insights into how the show is created come to the Wharf , Tavistock on Sunday, January 23.

The Archers Road Show 'Roots to Radio' will feature BBC Radio 4 actors Michael Lumsden who plays Alistair Lloyd the vet, and Felicity Finch who is David Archer's wife Ruth. Also taking part will be senior producer Keri Davies and sound effects expert Karen Burchell.

'There is a lot of interest. People always have a lot of questions about how the show is made,' said Keri.

'One of the BBC's policies is to be accountable and there is nothing more accountable than standing before an audience. Because the Archers have a following built up over many years we are fortunate that we can find out what people like or dislike.'

A former RAF officer Keri became involved in marketing and publicity before joining the BBC. A short term opportunity came up to work with the Archers' road show which led to the chance to direct. And this piece of good fortune led to him being finally appointed senior producer.

A self-confessed Archers fan, Keri, 41, says he is a 'relative newcomer' to the BBC having joined in 1992.

'I was incredibly lucky. There were a lot of good people around and the actors were very kind to me.'

There is a team of nine scriptwriters who attend monthly script meetings and each write a whole week of scripts.

'I'm part of the team that helps develop the stories. Anyone of the team can come up with story lines,' said Keri.

Far from being a problem sustaining the dramatic content of a show that is fast approaching its half-century there is always a surfeit of bright ideas.

'It is a case of which good idea do we have to put to one side because there are so many inventive people on the team. We have the luxury of coming up with some wild and whacky ideas.

'But ultimately we aim for a combination that stretches some people, is too radical for others but keeps most of the people happy most of the time,' said Keri.

Yes, he agrees the show has changed and evolved, broadened its brushstrokes from the farmyard to the winebar as well as the Bull.

'One of the reasons it is still with us is that it has changed. If we remained the sort of cosy rural drama Dr Finlay's Casebook was we would have gone the way that did.

'The countryside has changed dramatically since the 50s with redundancies of people working on the land and the incomers.'

The original purpose of the Archers was as an entertaining way to get educational messages across to the farming community. But its popularity vastly outstripped such expectations making it compulsive listening whether you lived on the land or the top of a tower block.

'We have 4.5 million listeners a week which is the most listeners for any radio drama — and bigger than some of the more minor TV soaps,' says Keri.

'These characters moving around the chessboard of life have been around longer than I have.

'Norman Painting as Phil Archer was in the first episode and has reached the Guinness Book of Records as the longest serving actor in a single role.'

The character of Phil is 75 years old and, as Keri points out, writing the script has to present him as a real person with a long history.

With a successful series like the Archers any plot scripted in the present could have far-reaching repercussions in the show's long term future.

'We have to be very careful with the 50th anniversary coming up because we are very proud of our history. It is a national institution but as a programme it has to earn its crust every day because there will be new listeners. We have to appeal to them and give them stories they want to hear.'

When David and Ruth Archer were having their second child the script-writing team had a long debate about what the sex of the child would be as the first was Pip, a girl.

'If it's a boy in 20 years maybe he would want to be the farmer so there might be an interesting dramatic battle there. What other programme thinks 20 years ahead?' said Keri.