By Li-mei Hoang

LONDON (Reuters) - There can be no greater tension in the fashion world than the brief moment just before the music starts, the lights blaze and the models hit the catwalk.

The collection is ready, top editors, buyers and journalists wait by the runway with baited breath, models get last minute attention and designers pray that months of effort and expense will be rewarded with critical and commercial success.

For designers, the prospect of spending an extraordinary sum on glamorous venues, booking the best models, set production costs and marketing, is a risk many are willing to take to be exposed to the international press and the top buyers who flock to London for its groundbreaking designs and fresh new talent.

"I think the idea of doing a catwalk show at London Fashion Week is a huge investment for a designer and obviously not one that we would really encourage them to do unless they're really ready," British Fashion Council Chief Executive Caroline Rush told Reuters.

"But the images that come from that, and the marketing material and the collateral, last a good six months, so if you amortize that over the six months in terms of the coverage that you can achieve and the audience that reaches, if you can do it, it is a really great investment."

The fashion industry remains notoriously cagey about the exact figures spent on catwalk shows. Not surprising given the lavish displays on show in New York, London, Milan and Paris.

Chanel Designer Karl Lagerfeld is famous for extravagance, having once erected a huge iceberg in the middle of the glass-domed Grand Palais in Paris, just to accentuate a chilly theme.

"We know that some of our designers do their shows for 30,000 pounds ($48,700), but we also know that the brands spend an awful lot more than that in terms of the staging, the setting, the build, creating that whole brand environment," Rush added.

With such a hefty price tag, it is not surprising that coming up with the funds can be a struggle for new designers and particularly in European and North American markets wrestling with weak economies and a Euro zone crisis alongside shrinking corporate and household budgets.

"Right now, the economic crisis really makes the young, new labels hard to survive. If you don't have the mentors, industry experts, financial support, it's really hard to continue," designer Haizhen Wang told Reuters.

Haizhen, along with Vita Gottlieb and Teija Eilola are getting support from fashion business award Fashion Fringe to host their first catwalk show at London Fashion Week.

It is a big moment for the designers, who have been preparing their debut collections, and learning about how to run a fashion business successfully with the help of guest judge Christopher Bailey, chief creative officer of Burberry.

"It's an amazing opportunity to be able to have a fashion show," said Eilola. "Obviously, a fashion show is about creating more of an event of showing the collection, rather than just saying these are the sketches, these are garments."

"It does help you to give yourself and everyone else who is interested in the collection, an excitement about it," she added.

Former Fashion Fringe winner Corrie Nielsen has built her name up from her first show to become a highly successful and sought-after label. She won the prize in 2010 and recently showed her latest collection on Friday to hundreds of guests.

"It's exposure to the world," Nielsen told Reuters. "It's also your name and where you're at. The more you do it, and the better you become, the bigger name you get, it all has to do with PR and promoting it, marketing, everything."

But a catwalk show is no longer the only way fashion labels can gain themselves international exposure. Designers such as Eudon Choi, Emilia Wickstead and Dion Lee are all opting for presentations this season.

"With a presentation you often get see the clothes a lot closer. Last season, Richard Nicoll did a presentation, which actually got him a lot more attention than if he had done a runway show. It was perfectly executed and held at the ICA gallery and it became a really intelligent way to show his collection," Tilly Macalister-Smith, Acting Fashion Editor of Vogue.com, told Reuters.

Designer Emilia Wickstead, who chose to hold a salon show, said she wanted to bring back a sense of intimacy.

"Sometimes in the fashion industry, we all get carried away doing these crazy things but it's as important to me for a garment to be beautiful on the outside as well as on the inside, and I love keeping the intimacy."

Presentations don't work for every brand however, as designer Alice Temperley found.

"For us, it didn't work because the clothes needed a kind of romance, and being brought to life," Temperley told Reuters.

The need to stage a catwalk shows will never die out, said Macalister-Smith.

"The sense of pomp and circumstance, romance, fantasy and drama that is evoked from a catwalk show is absolutely crucial to the industry," she said.

"I don't think that the method of a catwalk show will ever die because it clicks inherently with something in the human condition, that we want to be invited, we want to be seen, you want to see who's there, you want to see the clothes."

(Additional reporting by Piya Sinha-Roy, editing by Paul Casciato)