While many of the activities associated with prostitution are illegal in the UK, paying for sex is actually legal and as a result, prostitution services are widely marketed on the web.
Dataviz built using UPDATE: a follow-up piece with new revised data and calculations is available here. According to the Office of National Statistics the answer is 60,879.
In figures due to be released next week this number is being used to add £5.314bn to the official size of the UK economy.
But the ONS only attempted to measure the number of female prostitutes.
If male prostitutes are included in the count then the contribution that prostitution makes to the UK economy rises to £8.856bn.
From the 30th of September the UK’s national accounts will attempt to measure illegal transactions to which all parties consent, including the sale of illegal drugs and prostitution.
Illegal transactions are difficult to measure because the participants, while willing, are anxious that their business goes unnoticed.
As a result there are very few obvious ways to directly measure illegal transactions and the ONS have been forced to rely on 10-year-old survey data in order to try and estimate the level of prostitution activity in the UK.
But there is a better way of measuring the number of prostitutes than using survey data.
There are two main problems with the ONS using the Eaves study in this way: Eaves only surveyed the sex industry in London and Eaves only surveyed women working in the sex industry. In order to do the work we built an extractor to the website Adult Work.
Adult Work is an online marketplace for adult service providers.
We chose to perform our analysis on Adult Work because Adult Work is much more popular relative to other similar websites.