Inside the £160 an hour brothel above a bookies at centre of Martin Sorrell scandal

Behind the plain white front door is a lurid pink sign announcing ‘beautiful model’ and wooden stairs leading up to a one-bedroom flat.

Visitors are ushered into a generous room with a king-size bed adorned with neon red fairy lights. A leather jacket, bondage gear and racy underwear hang on a rack behind the bedroom door.

This was the scene at 50a Shepherd Market, a nondescript flat above a bookies. But being in the heart of Mayfair, this flat, which once belonged to a peer, is worth £1.3million. Now it is rented by the day, by a variety of young women who sell their bodies for sex – often to men who turn up unannounced.

The brothel on Shepherd Market in Mayfair, Central London where Sir Martin Sorrell is accused of using WPP cash to pay for sex

‘The young lady will be with you shortly,’ a middle-aged dark-haired woman, the flat’s maid, said in a strong northern accent when the Daily Mail visited yesterday. Seconds later, the young lady, clad in black lingerie and wearing black high heels, could be seen sitting cross-legged in a tiny waiting area.

She looked in her mid 20s, was about 5ft 5in tall and of slim build. She had straight black hair, longer than shoulder length, and wore dark mascara. She spoke with an eastern European accent. Seemingly shy but cautiously friendly, she did not wish to give her name and said she operated on a ‘no questions asked’ basis.

Inside the bedroom there is cream acrylic carpet, burgundy wallpaper and dimmed lighting. Thick dark curtains are pulled tight across windows that look out on Shepherd Market, a favourite playground of expensive bars and restaurants for the capital’s wealthier residents.

Sir Martin Sorrell is accused of using WPP cash to pay for prostitute in Mayfair

Seedy: The sign on the Mayfair doorway that leads to the flat used by prostitutes, with a 'beautiful model' sign 

Seedy: The ‘beautiful model’ sign on the Mayfair doorway that leads to the flat used by prostitutes, where Sorrell is said to have visited

Speaking softly, the woman nervously ran through the price list. For £60, clients get a 20-minute session. It costs £160 for an hour of ‘whatever you want’.

The flat, above a ground-floor branch of bookmakers William Hill, has an en-suite bathroom and a rudimentary kitchen. The walls are bare, apart from an A4-size silhouette image of a woman.

‘I rent this apartment for my business for one day a week, every Monday,’ she said. ‘We don’t really know the other girls who work here. I don’t see anybody else. We just leave some money in the microwave to pay the rent. Some people come back lots of times, some people only visit once. We don’t ask them personal questions because they don’t want to answer them. They just come in, do their business, and then they leave.’

According to a website which reviews brothels, women named Bianca, Elly, Priya and Suzzanna are said to work at 50a Shepherd Market.

Suzzanna, who works on Tuesdays – the day that Sir Martin Sorrell is alleged to have visited the flat on June 6 last year – is described as ‘brown-haired and curvy’.

According to the Land Registry, the flat seems to have once belonged to the 6th Earl Howe, the Right Honourable Edward Richard Assheton Penn Curzon, styled Viscount Curzon. He died in 1984 aged 75, and the flat was left in his will. It is unclear who now rents it out but the will’s executor, Michael Williamson, is named as the proprietor in the Land Registry records. He was unavailable for comment yesterday.

Shepherd Market’s seedy reputation dates back to the 1980s when former Tory Party deputy chairman Jeffrey – now Lord – Archer, paid a prostitute for sex, the late Monica Coghlan, after meeting her in Mayfair.