Walk into any phone-booth in central London and there is a familiar sight - a colourful montage of hookers' calling cards advertising "18-year-old models", "wild Mediterranean flowers" and "African princesses".
But aside from the grainy photos of scantily clad girls in provocative poses, 90% of the cards have one other thing in common: next to the offers of "domination", "kinky massage" and "schoolgirl spanking" - the words "hotel visits available" are also likely to be evident.
Hookers and hotels share a time-honoured link. Watch the movies for confirmation, from the gritty, bloody realism of Mona Lisa to the anodyne romanticism of Pretty Woman.
The anonymity of the average hotel, and the conspicuously large numbers of beds, make them natural venues for sexual liaisons of every kind. Indeed, the phrase "room service" takes on a whole new meaning when said with a sly wink. Behind closed doors, managing directors lie down with secretaries, escort girls entertain business executives and whores massage the egos of film stars.
However, the steady marriage of the sex industry with the hotel trade remains the latter's great unspoken secret. While it is only infrequently discussed, everyone knows it goes on. Nearly all the hotel concierges who were approached for this feature were honest enough to admit that prostitution occurred within their walls, though most were quick to add that, whenever prostitutes were clearly identifiable, security staff were quick to steer them back on to the street.
The methods by which prostitutes gain access to hotels vary. Sometimes they are booked directly into clients' rooms under the guise of wife or girlfriend. Others use hotels as free-range hunting grounds for potential customers. Most busy London hotels are crammed with the easy targets of bored executives, away from home on business, and probably already tired of the tame, soft-core porn on offer on TV in their rooms. The painted ladies to be found in dark corners of bars or basement nightclubs and the miniskirted figures cruising corridors for business or loitering outside the reception area can help relieve the monotony.
Of course, once the transaction is agreed, there is the matter of smuggling the prostitute up to the room. However, the average international hotel is so chock-a-block with arrivals and departures that it is not especially difficult to dodge the suspicious stares of staff. As long as the guest looks respectable, doesn't make a scene, has booked a double room and pays the bill on time, hotel staff are unlikely to closely question the nature of any female visitors. And as long as the woman does not draw undue attention to herself or solicit too obviously, she too may pass unnoticed.
"Natalie" works as a prostitute in central London. On her calling card, she is depicted as a pouting "17-year-old" nymphette, sporting a thick blonde fringe and white negligee, although on the phone she sounds quiet and shy. She is regularly summoned to hotels, "generally those with four and five stars. They just call you out and you go and find their room number."
In Pretty Woman, Julia Roberts' tart-with-a-heart attracts unwelcome attention when she strides through a hotel lobby decked out in stereotypical hooker gear: micro mini, kinky boots and no bra. Unsurprisingly, she finds her cover easier to maintain when draped round Richard Gere and clad in Alberta Ferretti-style frocks and expensive diamonds.
Similarly, it is a myth that all prostitutes fit the classic "street" stereotype. Dodging staff, says Natalie, is easy if you make the effort. "I dress conservatively so they won't recognise me," she says. "They can't do anything." Carrie Mitchell of the English Collective of Prostitutes (ECP), which campaigns for legal rights for prostitutes, affirms: "A lot of women make sure they are not identified in the hotel."
The most natural point of contact between staff and hookers is the front entrance or lobby. But sometimes it is hard to tell, and mere suspicion is not enough to justify action. Baggage porter John Fitzsimons of the Mount Royal hotel at London's Marble Arch says: "We see it once or twice a month. You get an older man coming in with a woman who is obviously not his daughter. What can you say?"
Billy Bostock, who works in the bar at the Mount Royal, says: "You get them coming into bars and sitting there all by themselves. There is nothing much you can do. Legally you are allowed to serve them at the bar, until you actually see them soliciting."
It's no wonder that innocent single women staying in hotels hate going to the bar alone. False accusations can cause Basil Fawlty-style blushes all round. As one security guard at a central London hotel popular with international visitors says: "You get prostitutes with Gucci handbags and £2,000 Chanel suits. What are you going to do?"
An industry insider adds: "A lot of these women are fabulous-looking, really immaculate and beautiful. Some of them get paid thousands of pounds."
The prostitution problem is by no means restricted to the hotel trade. The bars of certain well-known top London restaurants draw high-class hookers, who buzz round men in Paul Smith suits out looking for some action. Again it is tolerated, mainly because it can be hard to distinguish the working girls from well-dressed young women out for a good time.
When they can be identified soliciting near a hotel doorway they are moved on swiftly. Philip Mendonca, concierge at the five-star Le Méridien Piccadilly hotel in London, says: "You quickly kick them out or call the police." But he admits that, at the end of the day: "It is up to the client's discretion. All he has to do is register another person in his room. You can't stop them."
While prostitution inevitably is more common at those hotels situated in busy city centres or at airports, no establishment is immune from the phenomenon. But if a hotel gains a reputation as an open house for prostitutes, it could potentially snowball into a serious image - not to mention legal - problem.
Prostitution undoubtedly goes on in all types of hotel, from the stereotypically seedy motel and King's Cross hovel to the swanky five-star. But London prostitutes cite the more upmarket hotels in areas such as Park Lane as the most popular venues. The implication is clear: these hotels are magnets for rich international travellers well-versed in sex industry etiquette and armed with wads of disposable cash.
"Sindy", who describes herself as a tall, leggy, beautiful blonde, is regularly escorted to expensive London hotels. In her opinion, neither client nor hooker is doing anything wrong: "If a man is paying £200-£300 a night for a five-star hotel, I'm sorry, they are entitled to have some fun."
If prostitutes are not obviously available, guests may discreetly ask staff where they can be found. Shahid Jolil, concierge at the Britannia International hotel in London's Docklands, says: "We don't organise them but we do get asked to try to get hold of them. All we can do is point people in the right direction. But they would be stopped if they tried to bring them to their rooms."
With prostitutes apparently in such hot demand from international guests, it is not unheard of for corrupt hotel staff to cash in. They may build up relationships with local pimps, organising "lady friends" for guests while pocketing a cut for themselves.
Some get away with it, others do not. Billy Bostock says that, in his previous job at an upmarket London hotel, the entire bar staff were sacked for arranging such entertainment. Meanwhile, one industry insider claims: "A lot of times, a businessman can get what he wants through the concierge."
In other establishments, the staff may simply turn a blind eye - if asked very nicely. But the ECP's Mitchell says: "Often, staff want paying for keeping their mouths shut."
At other times, the sex trade may be positively encouraged. If vicious rumours can be believed, at one north-west London establishment, where prostitutes have been seen to solicit blatantly in the immediate vicinity, empty rooms go for £20 each at 2am.
In some cases, hotel staff moonlight as prostitutes, says Mitchell: "Yes, it happens. Women from all walks of life top up low wages this way."
One very natural fear that hotel managers have is of the eruption of unsightly scenes - if, for example, an angry prostitute is denied access to her client and thus her fee, or if a client refuses to pay the full amount and the prostitute's pimp arrives to claim her dues.
While prostitution is undoubtedly a problem for the hotel trade, London's Metropolitan Police were unwilling to be drawn on the subject. However, they did say that the most common problem was not with the girls who come in off the street but with men using established, advertised escort agencies, where the line between legal and illegal sexual services is less well-defined.