In the 1970s, Redbridge boasted Europe's largest Jewish population of 30,000. But a gradual decline as younger members decamped to north London accelerated between 2001 and 2011, during which it lost almost a third of its remaining population, falling from second to sixth among UK communities. In Clayhall alone, the number halved from 2,599 to 1,299.

Based on 2011 Census data, the Institute for Jewish Policy Research (JPR) calculated the community - a "thinning area" with "high death rates" - at just over 10,000. A JPR spokesperson suggests that the figure has since fallen further. "The direction of travel is very clear."

Now local leaders are looking to find ways to maintain a shrinking and more geographically diverse population. Merger has been one method, Clayhall United Synagogue recently joining forces with Newbury Park to create Redbridge United Synagogue. Wanstead and Woodford Synagogue amalgamated with the independent Waltham Forest Hebrew Congregation to establish Woodford Forest. The local Progressive synagogues, Bet Tikvah and Woodford, have also announced that they are exploring the possibility of a joint congregation.

Former Clayhall chair and Redbridge US co-chair Mike Callaghan says "merging is strength. I think we've given the area a massive boost.

"So far it's exceeded our expectations. Everybody's gelled very quickly. The people coming from Newbury Park have felt instantly at home. People who weren't sure about the future can now see that there is one."

Woodford Forest co-chair Sally Caplan also accepts the necessity of adapting to survive. "To do nothing would have been a weakness. It's a strength to come together to build for the future. They've lost their home, but we've lost our identity. There's been a lot of emotion, but we'll gain a lot of things."

At Ilford Federation Synagogue - which in 2013 moved from its long-time Coventry Road premises to Beehive Lane, 200 yards from Ilford United Synagogue - Rabbi Alex Chapper believes there is even potential for growth if the community plays to its strengths.

"We have increasing attendances because we moved to a new shul with a better location. We get about 80 people on a Shabbat morning. Before we moved they had dropped to 50 or 60. There's an eagerness to be innovative. We're always looking for new ways to engage members, like a comedy night we had recently with 100 people."

Local lay leader and charity fundraiser Gayle Klein says that preserving a sense of community in Redbridge requires more effort than in the major north London areas, where "there's a complacency. We are not blind to the fact that there may need to be more collaboration." The new Essex Jewish Community Council will certainly have a role to play. In its first plenary in February, members agreed that its main principle should be "that each organisation, shul, school or individual member must be mutually supportive - and be able to celebrate the success of others".

Declining numbers have also impacted on local Jewish schools, with vacant places filled by non-Jewish children. At Clore Tikva Primary, where 85 per cent of pupils are Jewish, headteacher Lenna Rosenberg says its ethos "is very much about respecting each other, whatever church, shul or temple you go to". There is African art on the walls and Chinese New Year decorations hang from the ceilings.

"Obviously the majority of pupils are Jewish, but we are an inclusive school so we have non-practising children, children who are Orthodox and everything in between - Masorti, Reform, Progressive."

At the Wohl Ilford Jewish Primary - which has followed the collaborative trend by moving to the Barkingside campus of King Solomon High - governors' chair Ben Saltman accentuates the positive of showing non-Jewish pupils what Judaism means. "In today's society we teach British values, and as well as teaching Jewish values, I think we have to learn about other values, too.

"We're a light in the Essex community. I've grown up here and have a passion to see it thrive."

Yet explaining the background to the Clayhall-Newbury Park merger, Mr Callaghan admits that both shuls could have faced closure in coming years if continuing to go it alone.

"The whole area has suffered a massive decline. What we've done is ensure that there will be a shul for the next generation. I don't think there's much chance of getting another kosher restaurant here. We've got enough shops to just about cover your basic needs."

Mrs Rosenberg now shops in north-west London for kosher food. "We support our local Jewish business, including both butchers, but…"

Her husband, Laurie, who manages Clayhall-based Redbridge Jewish Community Centre, contends that those who "wring their hands about Redbridge don't live here. It's a sin to say that we're in terminal decline."

Jon Jacobs, who manages Maccabi GB football teams at RJCC - including new Division One champions Jewish Care B - says there is a stigma about the area in the eyes of some north-west Londoners. "We don't help ourselves because we just concentrate on the negatives.

"We've had two teams pull out of games this season simply because they didn't want to come to Redbridge. We're part of a wider community, but there's still this superiority complex from north-west London. What we seem to forget here - and have done for 15 years - is to get the young in. If we provide the services, you've got them for life."

If attracting and keeping young families is the barometer of success, the nearby United congregation in more upmarket Chigwell is excelling. It is the fastest growing US shul in the country, with 69 families joining in 2014, making around 730 in total. Chigwell minister Rabbi Baruch Davis attributes this to a warm and welcoming atmosphere, but also to the area's changing demographics.

"There has been a shift out of Ilford, northwards to Hainault, Chigwell, Epping and Waltham Abbey," he explains. "And with the merger of Newbury Park and Boundary Road [Waltham Forest], people who might have joined us, but didn't because of emotional ties with buildings, can now do so."

Rabbi Chapper recalls that "about seven or eight years ago, we lost quite a few young families when there was an exodus to other areas. But the decline has slowed and we've stabilised."

But as Ms Klein explains, a "potential problem is not having enough young people to help care for old people".

There is high demand for places at Jewish Care's Vi and John Rubens home in Gants Hill. With 105 beds and an average residency of two years, the home is usually 95 per cent full. Norwood operates a variety of programmes for children - both special needs and mainstream - and tailored services for struggling families. The Gift food distribution charity assists a small number of families.

Jewish Care fundraising director and Redbridge resident Daniel Carmel-Brown acknowledges that the rising proportion of elderly people heightens the welfare requirements.

"There's no secret that we're looking at investing in the provision of a whole range of care services for the area in addition to what exists. What gets left behind in communities which gradually decline is older people.

"The community has changed and the demographics tell one story. But the other story is of a community which remains significant in numbers and vibrant at its heart."