The writer remembers the homeless woman who lived in his driveway for 15 years and inspired The Lady in the Van: a book, play and now a film

“No one knew her well,” said Alan Bennett of the lady who lived for 15 years in a van outside his house. “Even I didn’t know her well. But I knew what she was like.”

It was a very precise distinction: the ability to describe someone, to be so familiar with her presence that you can evoke her peculiarities, is not the same as friendship. The lady in the van had no friends, but she did have a neighbour, and that neighbour was a writer.

In 1989, after her death, Bennett wrote a long article, partly in diary form, about the time she had spent living in his front garden. It has since become a book and play, and now it is about to be released as a film, The Lady in the Van, with Maggie Smith playing the title character, Miss Shepherd, as she did on stage. At the Hay Festival, Bennett reminisced, alongside the film’s director Nicholas Hytner, about the fictions and facts of "Miss S"’s life.

The pair showed a few early clips of the film, in one of which an imperious and determined Maggie Smith explains the rationale behind her parking: “I’ve had guidance from the Virgin Mary,” she says. “She was outside the post office on Parkway.”

The film was shot in the actual house on the actual street where the events took place – Gloucester Crescent in Camden Town. Some of the same people still lived there when the star prop arrived, decades later. “I imagine they shuddered in horror as the van made its way back into the street,” said Hytner with a smile. The film director Stephen Frears, who during Miss S’s residence spent a good deal of time in the crescent visiting his children, heard they were making a film about her and said: “The world’s gone mad. You might just as well make a film about Goebbels.”

In Miss Shepherd’s time, the crescent was full of what Bennett described as “liberal, slightly guilty intellectuals”. They didn’t feel they could get rid of her. “She’d sense this,” Bennett suggested, and when she felt it was time to move, she’d just take the brake off. “In about 1973,” he went on, “she got to the bottom of the curve, which is where I lived, and couldn’t go any further”.

Bennett explained that he invited her in off the street – thinking she would only stay for a matter of weeks – because his desk overlooked the van and he found her travails so distracting he couldn’t work. People would come past and kick the van, or hurl abuse at Miss S, and he found himself constantly having to intervene.

More recently, Bennett came across two fledglings that had been living in a bird box outside his new house. Both had fallen to the ground: one died instantly; the second fell but lived, and Bennett became acutely aware of the dangers it faced: cats, magpies, seagulls... The same was true of Miss S. "This may seem very comic or droll or fanciful," he said. "It was exactly the same situation."

Dame Maggie Smith plays Miss Shepherd and Alex Jennings plays Alan Bennett in The Lady In The Van Credit: Nicola Dove/Nicola Dove

Recreating Miss S's home for the film was not easy, and Bennett expressed his admiration for the film’s props department, who he called the “unsung heroes” of the production. “You could have mocked up the chaos,” he said of the van’s crowded interior, “but they actually did it in depth, so that there was filth all the way through”.

So convincing was the set, in fact, that one night when the producers had left the van unlocked, life began to imitate art. They arrived in the morning to find that, in Hytner’s words, “a couple of terrible old drunks from Camden had taken up residence inside”. An “ashen-faced art department” proceeded to evacuate the additional filthy contents.

In real life, said Bennett, the only subject that interested anyone was Miss Shepherd’s “sanitary arrangements”. “It was really a question of plastic bags,” he said, “Stout ones.” Very occasionally, she would use Bennett’s loo, which he would spend hours disinfecting afterwards. As he wrote in his original memoir in the London Review of Books, “it was here on the threshold of the toilet that my charity stopped short”. In any case, she evoked mixed feelings all the time: “One seldom was able to do her a good turn without some thoughts of strangulation.”

Miss Shepherd had such strong political opinions, and found the existing parties so misaligned with them, that she founded her own party, the Fidelius Party – which was, according to Bennett, “well to the right of Ukip”. She wrote pamphlets, which she distributed outside the local bank, and wrote slogans in chalk on the pavement. At Hay, Bennett confessed that she occasionally sent him to have the pamphlets photocopied at Prontaprint, and that he worried the staff there might think he’d written them himself.

When a member of the audience asked what Miss S would have thought of being immortalised on film, Bennett replied that she would have thought it was her due. She believed herself to be “a person of significance,” he explained. Here was a woman who had, after all, once sent a letter addressed to “Someone in Charge of Argentina” in an attempt to explain to General Galtieri that “Mrs Thatcher isn’t the Iron Lady. It’s me.” She fully believed she would become prime minister. “When I’m elected,” she asked Bennett, “do you think I shall have to live in Downing Street or could I run things from the van?”

Now Miss Shepherd’s papers are kept in the Bodleian Library in Oxford. Bennett, meanwhile, was awarded a handmade silver medal at the end of his conversation with Hytner: the Hay Festival Medal for Drama. He looked down at it, and mumbled that he found it impossible not to think of it as a chocolate coin wrapped in foil. The conclusion? Whether one is or isn’t a person of significance is merely a matter of opinion.

The Lady in the Van is released on November 13 2015