Prime Minister Gordon Brown may have admitted in a TV interview on Sunday night that he doesn't have his own private loo in his offices at Number 10.

But that hasn't stopped him joining a unique arts project in Bath to raise money to improve toilet sanitation throughout the developing world.

Mr Brown and his wife Sarah have both joined an impressive list of celebrities including Stella McCartney, Sarah Ferguson, Michael Crawford and Kenneth Branagh in a charity fundraising event which has seen them designing special signs to go on the outside of toilets.

Now Bath people will be able to discover these original signs for themselves by going on an art trail around 19 venues in the city which will be displaying them for the rest of February.

The Doorway to Dignity Bath Art Trail is the brain child of the Freshford–based charity Wherever the Need, which is aiming to highlight the fact that 40 per cent of the world's population do not have access to a proper toilet.

A host of celebrities along with local schoolchildren and artists have created designs using the traditional ones we see on doors as the base.

So if you want to see what the Dire Straits guitarist Mark Knopfler, actor Sir Derek Jacobi or Bath rugby favourite Olly Barkley think a toilet sign should look like then you will have to join the city art trail which will take you to venues such as Bath Aqua Glass, Mr B's Emporium, The Egg Theatre and Costa Coffee which are all displaying some of the artwork.

There is a prize – a year's supply of loo roll from Morrisons – for spotting them all.

Behind the fun aspect of the art trail there is a serious message.

David Crosweller, from Wherever the Need, said: "Hopefully, Doorway to Dignity will serve us in three ways. It will make people aware of the importance of sanitation to the 2.5 billion people, especially women, who do not have access to a toilet. We also hope it will get more people to know of our charity and the work it does - and it will raise money."

The way the scheme will raise that money is via an auction of the signs later in the year. In addition, people who go on the art trail will be able to support the charity by putting money in collection boxes at all the participating venues.

The charity wants to raise £200,000 which would help 1,000 people to have sanitation and water.

Mr Crosweller said: "With these in place, people have a chance of working their own way out of poverty rather than continual hand-outs.

"Poverty can only be alleviated through good health and work – and that's what we provide."

Details of all the venues are at the website www.doorwaytodignity.org or you pick up a leaflet from 4, Milsom Place where you can also see many of the best designs.