Canvey Island is the notorious Ukip stronghold chosen by Nigel Farage as the location to kick-start his 2015 general election campaign — in short, a place not necessarily wild about immigrants and foreigners. So when film-maker Riete Oord heard that a group of Charedi Jews were setting up an outpost on the island, her eyes lit up.

“It seemed utterly bonkers. I thought, ‘my goodness, how are these people going to survive?’”

Living on the edge of Stamford Hill for 25 years had given Oord ample opportunity to observe the sometimes scratchy interaction between the Charedi community and their neighbours. “A Jewish housing association wanted to turn a school opposite my house into flats, and the home-owners round here said: ‘Oh no! It’ll be all overcrowding and naff architecture.’ I was quite fascinated about the class thing and how the Chasids were frowned upon.”

To Oord, there was an obvious link between the frequent planning disputes and the fact that Stamford Hill was bursting at the seams. Already the largest Charedi community in Europe, the combination of rocketing house prices and large families made affordable homes scarce on the ground. Past attempts to settle in Hertfordshire and Milton Keynes foundered because of hostile reactions to people whose dress and lifestyle are seen as odd.

Canvey, an island in the Thames estuary known for its large oil and gas depots, is home mainly to working-class families priced out of East London. It was attractive to the Charedim because there’s plenty of space and housing is cheap, but it’s also just over an hour’s drive from the mother-ship in Stamford Hill.

The island community, close-knit and determinedly English, seems happy to accept incomers as long as those new arrivals try to fit in — which seemed unlikely from the inward-looking Charedim.

Says Oord, “This was a community that refuses to mix, and there’s so much research that says separation is a breeding ground for mistrust and prejudice. Eventually, social division becomes hate and exclusion, extremism is the result. But in communities where respect is shown on a daily basis — you know, saying ‘hello’ in the street, the joining in of shared activities — there’s much less racial tension.”

Already, though, there were signs of discord. Charedi families scouting the area for homes clustered near the shul had ruffled feathers. “The Canveyites say they are knocking on people’s doors looking for houses to buy,” says Oord. “Well, they are, because they all have to live in the same area, so once two families live in a road, others want to join them. But it gets people’s backs up.”

The BBC gave its backing to the project — and it’s not difficult to see the attraction of something so fraught with the gold-dust that progamme-makers call “jeopardy”. In other words, the risk that it could all go horribly wrong. But why would the media-shy Charedi community want to be television stars?

Uppermost in the mind of former Hackney Councillor Joseph Stauber was heading off the kind of hostility that had undermined previous efforts to settle outside Stamford Hill.

“We understood that the local community of Canvey Island should have an insight — it is very, very important that people should have the right idea as to who we are, and what we represent.” And, he adds, with a degree of perception that might surprise some: “they will realise we are not people coming from the moon, we are down-to-earth people. We do look funny, but we behave quite menschlich.”

Feeling that previous documentaries had poked fun at their community, they thought hard before placing their trust in Oord. An experienced film-maker, she spent years working with Nick Broomfield, then Britain’s most talked-about documentary director, on provocative subjects like far-right Afrikaner Eugene Terreblanche, and serial killer Aileen Wuornos.

Peeling off to direct in her own right, she’s made many documentaries and series for BBC TV and Channel 4 including Who do You think you Are? and the RTS-nominated Luton Actually. The theme she seems to return to constantly is that of the outsider.

It is not hard to see why. The child of Dutch parents, she was brought up in Pakistan where her father was working for Shell and the dominant expat community was British.

“They repeatedly refused to let me into their school, so I became very competitive in sports — I started sailing and swimming and started to win, so finally they let me in.”

Sent off to boarding school in England at the age of 12, she found herself the object of curiosity once more: “and I just had to work really hard to fit in.”

It certainly paid off — nowadays, Cambridge-educated Oord speaks English without a trace of accent. And though nobody would label her an immigrant, she retains an almost anthropological fascination with assimilation.

Canvey: The Promised Island is about the kind of fallout you get from one group being transplanted into another.

In the film, the Jewish side of the story is represented by Naftali Noe, a young father who wants a better life for his family, and his Stamford Hill neighbour Steve Brown, whose role in the film is to explain the mysterious Charedi lifestyle (declaration of interest: he’s my husband!)

The Canveyites are shown as being curious and cautiously welcoming to their strange new neighbours. One of the principal characters is Chris Fenwick, manager of local ’70s rock band Dr Feelgood and owner of the island’s main hotel. Determined to facilitate smooth integration and offer the hand of friendship, he hosts a meal to break the ice between the two communities. The event emerges as an odd assembly of black hats on one side and tattoos on the other. For a moment, one feels, things could go either way.

In Oord’s view, the Canvey islanders are actually far more welcoming to the Charedim than her middle-class neighbours in London’s increasingly desirable Hackney. “They don’t have the same prejudices. You’ve got these people who are in a way more outwardly racist, but actually it turns out they are more open. They don’t bulls***, they say: well, these people are different and who knows what’s going to happen? But let’s give it a go.”

She reflects, “Making this film was fascinating because it’s about race, class and religion. But, as Steve says, it is also about hats — about how you look different. It’s about a community that separates itself visually.”

The moment of truth arrives on a Sunday morning in August. Joseph Stauber has come to view an early cut of the film. His endorsement is pretty vital to maintain cordial relations with the Charedi community, but this film will be broadcast by the BBC, which has a strict code of conduct about how much contributors are allowed to interfere with editorial content. If Stauber really objects to a particular scene or line of commentary, things could get sticky.

He watches the film thoughtfully then pronounces his verdict, “Very good, it’s beautiful. Well done!”

Riete Oord breathes a sigh of relief and sets off to apply the finishing touches.

Canvey: The Promised Island is on BBC 1 on January 9. 10.45pm