Computers in the Houses of Parliament for MPs, civil servants and peers have been used thousands of times to visit a website for people seeking affairs.
The adult dating website Out of Town Affairs, which offers "unsatisfied married men and married women" the chance to "do the dirty of their partners whilst out of town" received an astonishing 52,375 hits in seven months from computers used exclusively by those working in the UK's seat of government,
In December, the site had more hits from parliamentary computers than the official websites of the Treasury, Ministry of Justice and Department for Education.
The website, which contains explicit photos of subscribers, boasts: "At Out of Town Affairs we connect you with thousands of other married men and women who are looking for a marital affair or more heat in the bedroom, the variety of new members is fantastic."
For a £25 monthly fee, users are invited to "write your own sex date diary" and "read and send filthy messages".
The figures were obtained by the Mail on Sunday following a Freedom of Information request for the 500 websites most visited by parliamentary computers over the last year.
In December, the website received 8,457 page views from computers based in parliament. In November, it received 7,533 hits; in October, 8,971 hits; in August, 5,174; in July, 7,493; in June, 6,822; and in February, 7,925.
The owner of Out of Town expressed surprise that lawmakers, lords and ladies were spending so much time hunting for illicit liaisons.
"That's a lot of hits," he told the Mail. "It's got to be more than one person going on the site from Parliament. I hope we don't get hate mail from parliamentary wives now."
Those working at the the 'mother of parliaments' also spent their time on gambling sites, gaming sites, watching videos and chatting to friends on social networking sites.
Chess and solitaire sites were popular, while i-am-bored.com, featuring 'viral videos, games, memes, lists and social networking for when you're bored', had 21,371 hits in the last three months of 2012 alone.
Online games such as FarmVille, Fairyland and Mafia Wars were also popular, while grooveshark.com, offering chart hits, received 709,740 hits in a year.
Facebook received an incredible 28 million hits over the year.
A Parliament spokeswoman said "more than 5,000 people" had access to parliamentary network computers but that the Out Of Town Affairs website broke IT rules and has now been blocked.
"We allow people to use the computers for personal use in non-working hours."