Tributes flowed around the world when the iconic Bloom's restaurant in Golders Green finally closed its doors in 2010.

But while the likes of Steven Berkoff, Maureen Lipman and Giles Coren mourned its demise, others questioned how such a supposedly popular eaterie, which first opened in Whitechapel in 1920, could end up going into liquidation.

Bloom's demise is partly attributable to a change in diners' habits. British Jews are no longer content with simple Ashkenazi dishes similar to what their grandmothers served throughout the last two centuries. Now the demand is for as full a range of restaurants providing kosher versions of world cuisine, much as customers in the non-kosher market would expect.

Rabbi Jeremy Conway, of the London Beth Din's kashrut division, said the number and range of restaurants on offer in north west London - and the inevitable question over supply and demand - was under constant discussion.

"There has been an incredible change over the past decade. Once we were amazed to have six restaurants; now it's changed out of all proportion. It's very exciting from our perspective," he said.

Facts

First kosher restaurant was Bloom's in Whitechapel, which opened in 1920
Applications for kashrut licences have dropped in the last year
Demand for more sophisticated kosher dining has expanded to kosher Indian and kosher Chinese, as well as the near ubiquitous love of sushi

It is thought there are more than 40 kosher eateries in the capital, licensed by the LBD and other kashrut authorities such as the Federation of Synagogues Beth Din, the Sephardi Kashrut Authority, and the Union of Orthodox Hebrew Congregations' Kedassia.

Rabbi Conway understands the difficulties that proliferation creates, but said: "Obviously it looks different when you have had a long-standing, successful business. It has been suggested that we should refuse to give new licences and protect the older venues, but we have to do what is best [for the community]. The more restaurants the better."

The difficult economic climate has had an effect on the industry. Applications for new kosher licenses are down, and several restaurants have revamped their style of food and decoration - or even moved location.

Bloom's has not been the only place to close in the past two years. The first attempt at a kosher pub - Fernandez in Hendon - came and went, as did Edgware pizzeria Tutti Gusti. Yet Tira, a new kosher pub in Golders Green, opened last month, and its owners hope to land significant business by hosting simchahs and charity functions.

So why do it? What attraction can there be in entering such a difficult market, with a limited number of customers to attract in tough economic times?

David Steinhof, director of the Sephardi Kashrut Authority, said last month that diners witness busy restaurants in the evening and imagine the money pouring in, but the unsociable hours and daytime empty tables go unseen. It takes at least two years, he believes, for a restaurant to establish itself and survive.

Jacques Marciano, owner of White Fish restaurant in Hendon, opened his business last year after a career in the fashion industry. His decision was based on a "passion" for food, but his desire to run a restaurant was such that he went ahead, despite understanding the difficulties.

He said: "I waited for an opportunity and I saw an opening for a nice fish and chip restaurant. I went through all the kashrut issues with the London Beth Din. They looked at my background and my kids' Jewish schooling, everything. We had meetings with the dayanim. It was a very thorough process.

"You wonder why so many kosher restaurants open and close quickly and the failure rate is perceived as so much higher than for non-kosher businesses. There are many reasons. There are more restaurants now but there are not more people wanting to eat in them.

"Businesses think they can do better or offer something that others are not already doing. But the community is demanding, and the kashrut demands make it harder too."

Mr Marciano said that something as simple as the washing of vegetables to ensure they are kosher carries a substantial financial burden. The process, he said, sees the loss of up to half his stock and the inevitable additional cost that incurs. Some kosher food items are hard to source, leading suppliers to charge restaurateurs ever-higher prices.

"Everything involved becomes so expensive, and that's a high proportion of the problem. If I can make enough to pay my bills I will be happy. It's really so hard to make money in this industry, that's why people come and go so quickly. It's a real challenge."

The streets of north west London may be lined with often empty kosher eateries, but the capital's centre, with its tourist and business markets, offers little.

Rabbi Conway said: "I understand the rates are so high in central London and that makes it very difficult. We have a long way to go to catch up with somewhere like Paris."

He said the declining Jewish population in provincial communities meant sustaining a kosher restaurant was ever-more difficult.

"You might try to open something one or two nights a week and if you can make an arrangement with your synagogue or community centre to have low rent and make it a family business with low overheads, then it might be feasible. But to have a thriving business you need a bigger community."

Despite that, there are plans to open a new kosher eatery in Ilford, Essex, and a number have already opened in Borehamwood, Hertfordshire.

In Leeds, where there are no full-time licensed kosher restaurants, community members eat at The Vine, a "pop-up" restaurant open two days a week at the city's Ziff Community Centre.

Diner Malcolm Taylor said: "Originally it was open every night but there were not enough people to sustain it. Now you can eat here on Thursday and Sunday evenings or Sunday brunch. It's reasonably well used.

"It does mean on a Thursday night it is pretty full and you will always see people you know. The food is always good and the menu changes every month. You find people come from Manchester to visit their friends in Leeds and eat here, rather than Leeds people going to Manchester."

Mr Taylor said experience had proved there were not enough kashrut-observant diners in Leeds to sustain a full-time restaurant, "but with The Vine it is a lot better than before, when we had nothing".

Commentators have often considered the increased number of restaurants to be something of an anomaly at a time when the number of people keeping kosher at home is perceived to be declining.

But the facts seem to contradict such beliefs. The latest version of the London Beth Din's Really Jewish Food Guide contains more than 7,000 licensed products available in Britain.

Michelle Teiman, a buyer at the Yarden store in Golders Green, said Jewish families wanted more sophisticated, adventurous home cooking options, developed substantially from what traditional kosher butchers once offered.

Jacky Lipowicz, chairman of the Licensed Kosher Meat Traders' Association, said new opportunities both in restaurants and at home were developing side-by-side, at no significant detriment to butchers.

"I supply quite a few kosher restaurants. One of the big ones I work with is the equivalent for me of supplying 100 homes a week. They do get it supplied cheaper because of the bulk purchase, but one compensates the other," he said.

"It's not counter-productive. We are offering people a wider range than ever before. Kosher restaurants have become more up-market and so the butchers have as well. You can now take a non-Jewish friend to a kosher restaurant and not be ashamed or embarrassed."

Mr Lipowicz said changes to work and living habits meant the kosher market has also had to adapt: "People like things pre-prepared now but many do still want to make their own chicken soup and chopped liver.

"But the world has changed, and with more women working, they want to buy ready-made kosher meals. We provide that and it is now easier to keep kosher. We are doing more to help the consumer."

He said that working with restaurants was helping kosher butchers, as consumers will enjoy a meal and then want to replicate it at home, asking the butcher to provide the same steak or lamb that they were served in the restaurant.

The general increase in food prices is being felt, however. Mr Lipowicz said kosher butchers were doing everything possible to keep rises – such as the 50 per cent increase in lamb prices – from consumers.

He predicted that as long as the volume of meat sold for home consumption remains steady, the cost can be kept down.

When it comes to kosher caterers, there is success at both the top and more budget ends of the market.

Big name, big price caterers, such as Tony Page, remain busy despite the economic difficulties families face, but businesses which offer more cost-effective simchah meals also report brisk trade.

Those working throughout the industry are agreed on one point - the importance of families having the option of an affordable kosher simchah, rather than a straight choice between an unaffordable kosher caterer and a non-kosher meal.