Officials anticipate that 32 million international and UK tourists will visit London this year. New walking tours are added to the city's to-do list annually. So, why not get to know London through its toilets?
Walking tours are big business in many cities around the world. They allow you to experience a place at street level and learn from a local guide. But, in London, a tour of the capital's toilets takes the visitor to another level - literally downward. By doing so, the tour guide promises, you will get to experience a totally new, and quirky, side of London life.
The group on the Loo Tour file down a narrow staircase to look inside a set of ladies' johns in an unusual location. This pub is one of many places across London worth visiting just for the toilet.
"Hello, and welcome to the Knights Templar," a man says. "I'm Will, one of the assistant managers here. We're downstairs to look at the ladies' toilets. The pub was a late '90s conversion from the Grand Union bank to what's now the existing pub. So, we're led to believe the toilets are situated in what were the vaults."
The door opens, and Will is right. There are gasps of amazement from the small group. Will starts to describe the room, noting that the toilets are situated in a long room with marble-effect tiled flooring.
"There is lots of marble here and lots of mirrors, which helps make the space even bigger than it actually is," Will says. Some visitors, he admits, come here just to look at the toilets: "Yes, they might buy a drink out of courtesy, but I think the fundamental reason for their visit is to see the toilets."
From high culture ... to low!
Guide Lucy Whitton introduces herself to the group and explains that the tour will run for an hour and a half, starting at Waterloo station on the south bank of the Thames River and eventually crossing to Covent Garden on the north bank.
Loo Tours began life three years ago, when the American Rachel Erickson was studying in the UK. She was incensed by the idea that there was money to be made out of something as universal as going to the toilet - which gave her an idea.
"I came to the city very much as a tourist, and as an outsider I was fascinated by London's history and culture, and I went on a lot of tours myself, and then had all this knowledge that I was very excited about," Erickson says. "So, I decided to become a tour guide so I could inflict that on other people who would pay me to do it.
"I was originally going to do a Shakespeare tour because that was very much where my passions were. But, in the process of talking to people and doing interviews, it gradually came out that I'd developed this obsession with where you could go to the toilet for free because, as a poor student, of course I didn't want to spend 50 pence on a toilet - you can get a chocolate bar for that. And so the tour has grown over the years from that. It started mostly as a 'here are the free toilets of London tour' and today it's more of a toilet history tour with some tips about where to go for free thrown in."
Illuminating a different side to life
In fact, the tour helps illuminate a side of London many might never see. Bells ring at the Church of St Martin-in-the-Fields, an Anglican church in the heart of London, just around the corner from Trafalgar Square. There has been a church on the site since Medieval times, but the current structure, with its Doric columns, was built between 1722 and 1726 by James Gibbs in a neoclassical style.
"We're here at St Martin-in-the-Fields church," Whitton tells the group. "St. Martin is the patron saint of beggars. This is said to be the church of the ever open door. And there used to be some graffiti in the ladies' loos which said it was the church of the ever open toilet. It is OK to use the toilet here for free, so if you go into the crypt they've got quite nice toilets down there."
London's not the only European capital with a tour of public toilets - there's one in Berlin for example. But it was in the UK where one of the first public flushing toilets was unveiled in 1851. Over the past decade, the British Toilet Association estimates that almost half of public conveniences have closed down. With property at a premium in the southeast of Britain, some have been imaginatively repurposed.
"Some of these public toilets have been turned into bars or cafes, and one person even has turned it into a flat," Whitton says. "But that means there's more need to know where to go in London."
Not just toilet humor!
Though one hears an awful lot of toilet puns on the tour, there's also a serious side to what the guides do.
"Currently 2.6 billion people do not have access to sanitation," Whitton says. "So, we talk about that and also we talk about things that are being done to try to solve that problem. People are quite shy and reserved talking about toilets and going to the toilet. What's interesting on the Loo tour is when I first mention poo, people start wincing, but by the end they've become quite used to it. And using humor definitely helps. If we in the West with all our lovely clean shiny toilets can be comfortable talking about issues around sanitation, we can help those in the developing world."
The group have mixed reasons for attending the tour. One woman says she was attracted by the tour's unusual nature.
"It was just a bit unusual, the thought of it, so my friend booked the tickets and said would I like to come?" she says. "I said, 'Yeah, sounds interesting, yeah.'"
Another man says: "My wife bought me the ticket. She knew I'd be interested in this sort of thing. I've always been interested in industrial history, Victoriana. She also says I spend a lot of my life on the toilet." He laughs sheepishly.
He's right. On average, we spend between 1.5 and three years of our lives on the toilet. So, finding out more about this act we all share maybe doesn't seem such a funny idea after all, especially when the tour illuminates a previously hidden side of London life in the bargain.