ITV2's drama The Secret Diary of a Call Girl, starring Billie Piper, has proved a hit with audiences, attracting just under 1.8 million viewers on its debut.
Piper is known for her time in Doctor Who and for her singing career
The first episode of the raunchy series recorded one of the biggest audiences for the channel since it began in 1998.
It also scored higher ratings than the programmes showing at the same time on BBC Two, Channel 4 and Five.
The drama is based on an online diary, written under the pseudonym Belle de Jour, which became a best-selling book.
These were entitled The Intimate Adventures of a London Call Girl.
Piper took the lead role of Hannah, a legal secretary who has a secret double life as a high-class prostitute.
The series was heavily marketed, with advertisements in magazines and on billboards, as part of ITV2's XXL Thursdays strand.
A spokeswoman hailed the viewing figures as "a fantastic result".
The channel followed the episode with the premiere of the third series of award-winning US show Entourage.
The comedy series, produced by Mark Wahlberg, was watched by 255,000 viewers.
The highest-rated show on a digital channel to date was a live Premiership football match between Manchester United and Arsenal on Sky Sports 1 in 2004, with an audience of 2.77 million.
Footballers' Wives Extra Time holds the record for most viewers on ITV2 - with just over 1.9 million viewers in May 2005.