Jam, Jerusalem and geriatrics are what most people associate with the WI. White-water rafting, abseiling and nude modelling are not.

But the two worlds have more in common than many would think.

Women's Institute membership has fallen by 50,000 in the UK in the last ten years.

In Sussex 50 branches have folded with ageing members no longer able to cope with the demands of running a group.

The crisis has left the organisation with no choice. It must modernise or die.

The future lies in the younger generation and the WI has launched a drive to recruit women in their 20s and 30s.

The message is simple - the WI is whatever its members make it. If parachuting and trips to beer festivals are what members want, that is what they will get.

Ann Webb, who chairs the West Sussex Federation of WIs, said: "The WI certainly has an image problem. The very word institute sounds clinical and dated.

"Most people think we're just the jam and Jerusalem brigade but there is more to us than that. Recently, we went gliding and one lady in her 80s had a great time doing the loop-the-loop.

"Whatever people want to do, we will try to accommodate them. To me, the WI is about fun, friendship and learning. It has something to offer everyone."

The WI is hoping a new film, Calendar Girls, will help to sex up its image.

The film, staring Helen Mirren and Julie Walters, is based on the story of a Yorkshire WI group who stripped off for a calendar to raise money for charity.

Berenice Blurton, chairwoman of the East Sussex Federation of WIs, hopes the new film will lead to a surge in new members.

She said: "If enough people from a particular area contact us, we may even set up new groups."

With more than 250,000 members nationwide and about 10,000 in Sussex alone, the WI is certainly a force to be reckoned with.

Prime Minister Tony Blair discovered to his peril the might of its membership when they slow hand-clapped his speech at the 2000 AGM.

The WI has recently campaigned against post office closures and called for a five-year ban on the growth of GM foods.

The group's approach has already won over a handful of younger women.

Tanya Eccleshall, 34, joined the Mayfield Evening WI two years ago.

She said: "I've not even tried any home-made jam yet but I've certainly made lots of friends. It's good to know there are all these women I can call if I ever need anything."

The East Sussex Federation is hosting a flower festival at Firle Place, near Lewes, today.

Women interested in joining are welcome to attend. Call 01273 472616 for details.

The West Sussex Federation is available on 01243 783134.