It was 40 years ago today that Den Watts, Arthur Fowler and Ali Osman kicked down the door of poor Reg Cox’s house on Albert Square to find the old chap close to death.

It was a dramatic start for the world’s first exposure to EastEnders - the BBC’s long-running soap opera, conceived to provide the network with the sort of twice-weekly ratings winner that ITV had enjoyed for so long with Coronation Street.

Many of us, at some point over the intervening four decades, have dipped our toes into the comings and goings of the good folk of fictional London borough Walford.

But for author Julie Wassmer, who lives in Whitstable, her relationship with the programme goes far deeper than most.

Because for almost 20 years she was a regular scriptwriter on the show - helping shape the storylines many of us remember.

Speaking to KentOnline to mark the show’s anniversary, she reveals some of the secrets behind the scenes, why writers could only have a maximum amount of minutes set outside, how tabloids used ladders to get a glimpse of future storylines and why she thinks the soap has lost its focus on its main ingredient.

“I really loved the characters,” the 72-year-old reveals.

“We believed in those characters and we shaped them and came up with storylines for them. We literally put words in their mouths.

“I do occasionally still watch it now, but I much preferred it when the drama came from the characters rather than the tendency for melodramatic storylines today.”

But she is also able to shine a fascinating light on the complexities of structuring a long-running show for which scripts are written many weeks in advance of the episode going into production.

She’d got the call to try out for the soap from her agent after she started to enjoy some success in the world of commercials and a short film for Channel 4 in 1989.

EastEnders first aired on February 19, 1985, and quickly proved popular. Its Christmas Day episode in 1986 - where publican ‘Dirty’ Den Watts famously served divorce papers to wife Angie - pulled in more than 30 million viewers. It remains the biggest UK soap opera audience of all time.

“I can't remember the year that I started,” says the author of the popular Whitstable Pearl books, “but it was obviously before 1994 because that was when we went three times a week. When I started, it was just twice a week.”

Today it’s upped its output to four episodes a week.

“I was thrilled,” adds Julie, “because I'd not really been interested in TV soaps like Coronation Street or anything. But I'd become hooked on EastEnders when I came back to London in 1988 [she’d been out of the country for several years] and I used to make sure that I always watched the omnibus [a re-run of the week’s episodes, back-to-back] on a Sunday afternoon.

“I grew up in the East End so its humour and characters struck a chord with me.”

She entered the world of Albert Square during a period of rich characters; Arthur and Pauline Fowler, Ian and Cindy Beale, Pat and Frank Butcher, and, of course, the Mitchell brothers and their mum - Peggy.

“They didn’t like referring to it as a soap opera, back then,” she recalls. “They always called it an ongoing serial drama.

“The characters when I was there were so strong,” she recalls. “I particularly loved writing for Dot Cotton.

“In one episode I had her cooking a cake for her husband, Jim Branning, and it was a Battenberg. So that became a feature; Dot always cooked Battenberg cakes for Jim.

“I remember when the Jackson family joined. The executive producer had this idea that Sonia would learn the trumpet. And the actress Natalie Cassidy actually had to learn the trumpet.

“She was quite good at it, but the executive producer didn't want her to be good at it. She was meant to be paying really badly. She was meant to go to the school concert and play and sing Nymphs and Shepherds. And I said, ‘look, I think it'd be much more exciting if she actually sang Madonna's Like a Virgin’. And so she did.

“It was little things like that that I remember - but we had some fantastic storylines.”

It will perhaps come as little surprise to hear that the process of writing, editing and filming each episode was logistically challenging.

Regular meetings would involve writers pitching ideas, along with those from producers, editors “and sometimes even the actors”.

“Every two months there would be story conferences with the producers, all of the script editors and several of the regular writers,” she explains, “and there would be a long-term planning forum.

“All these ideas would be collated and filtered and then there would be a monthly planning meeting.

“These would eventually develop into blocks of episodes for the week.

“By the time I left, in 2008 I think it was, we were going out four times a week, so there would be 16 episodes each month.

“They would then contact us, as freelance writers, and say do you want two, three or a whole week’s worth of episodes?

“The broad strokes of the stories for each episode would be plotted and it would then be down to you to progress the story.

“Obviously, it was much easier if you were given a whole weeks’ worth because not only did you have autonomy over that, but it was a lot easier for continuity.

“If, say, one week’s episodes were split between writers, you had to liaise quite closely as there was a much greater chance of us repeating material or both coming up with the same idea.

“That’s where the role of the script editor was so important, because they would be monitoring all your draft scripts, dealing with continuity and making sure everything locked together.”

Each writer joining the team was given the ‘writer’s guide’ - or EastEnders’ Bible as it became known.

“It included a whole section on the characters of EastEnders,” she explains. “There would be pages on the the likes of the Beale family and their history.

“Each character would have their own section with their date of birth and with important things that had happened throughout their lives.

“If it was deemed that a storyline was being given to one of those characters and we felt that just wasn't what the character would do, we would fight really hard at meetings. One thing I've always felt really strongly is that story comes out of characters.

“So if you're finding it hard to come up with storyline, always return to your character and your character will tell you where they want to be.

“What was difficult was when you felt a storyline was being grafted onto a character. While I was there, one of our characters, Mark Fowler (Todd Carty), was diagnosed with HIV, so if you had a character that was really being affected by an issue, like Little Mo later, when she was a victim of domestic abuse, we would really be fighting very hard that the issue didn't take over.”

There were also limits to what could be included in any given script due to on-set limitations of filming.

“It was really complex in terms of scheduling,” the writer explains.

“You’d have some permanent studio sets like the launderette and the Queen Vic for example, and then other sets would have to be put together if you needed them. And you could only have 10 minutes shooting on the Albert Square lot which was the exterior of all the properties or the market. I can’t remember quite why.”

EastEnders is filmed at the BBC Elstree studios in Borehamwood, Hertfordshire - home to the full Albert Square set we are all familiar with. Leaves are even attached to trees if spring filming will lead to a summer broadcast date.

Episodes are filmed around six weeks ahead of transmission, with scripts written weeks ahead of that.

Not that it stopped the tabloids trying to get wind of big storylines.

“I remember there was one big episode where there was a fire at the car lot,” Julie recalls. “I was there and I can remember all the tabloid newspapers sending down journalists who had paid to get into people's back gardens, close to the studio.

“They'd put ladders up and were trying to shoot what we were doing.

“It was after all of that, the show began to film and script different endings to fool the press so they couldn't come out with any spoilers.”

And what, I ask, about the end-of-episode ‘doof doofs’ - the famous cliffhangers?

“I learned very quickly about story structure and what was really important to us was to put a hook at the end of every scene,” she says.

“It hooked your viewers so they didn't go off and make a cup of tea and not come back again. And of course, in those days there was no opportunity for streaming or pausing it either. You couldn't catch up with anything apart from the omnibus on a Sunday.

“So you made the end of each scene dramatic and, of course, we had the doof-doof cliffhanger at the end to bring those viewers back again.

“The issue was you were never just dealing with one storyline - you’ve got a multi-character drama.

“You had to choose which one - but often we would determine what that final scene would be.”

Julie would go on to enjoy writing for other shows such as ITV’s London’s Burning before finally fulfilling her dream of becoming a novelist.

Her Whitstable Pearl books have now stretched to 10 books and have been dramatised on Acorn TV - with the seaside town providing the backdrop to the murder mysteries.