Rylan Clark, Lacey Banghard, Montag and Pratt: The famous for being famous enter Celebrity Big Brother house

Drug-ban horse racing champion Frankie Dettori, former Steps star Claire Richards and X Factor contestant Rylan Clark tonight entered the Celebrity Big Brother house after weeks of speculation about the line-up.

They are joined in the latest series of the Channel 5 show by ex-EastEnders and Footballers Wives actress Gillian Taylforth, model Paula Hamilton and former football star Neil "Razor" Ruddock.

One absentee is comedian Jim Davidson who had been due to appear but was dropped after being arrested and questioned by detectives over allegations of sexual offences which he denies.

Clark was installed as favourite to win the show by bookmaker William Hill, with Dettori next.

Also taking part in the new series are Neighbours star Ryan Maloney - who has played Toadfish in the Australian soap since 1995 - as well as former Coronation Street actor Sam Robertson and reality TV couple Heidi Montag and Spencer Pratt.

One-time Heartbeat actress Tricia Penrose and glamour model Lacey Banghard complete the line-up.

There had been rumours that wild-child Hollywood actress Lindsay Lohan would be taking part but she was missing from the list of stars who rolled up to the studios at Elstree, Hertfordshire, to enter the house.

The contestants will spend the next few days holed up in the custom-built property in full glare of TV cameras with a winner emerging later this month if they can prove popular enough with viewers and their own housemates. The series is expected to last three weeks, with the first eviction due on Wednesday.

Dettori enters the house just weeks after he was given a six-month ban from his sport after a positive drugs test, which he said had left him feeling "ashamed and embarrassed".

"It doesn't matter what I took or how much - what I can say is it didn't make me ride any better or make my horse run any faster," the Italian-born showman said after the ban, which followed a positive test in Paris in September.

Hamilton found fame after starring in a VW ad campaign, but went on to have a problem with drink and drugs. She dated music and TV mogul Simon Cowell when she was in her teens.

Montag and Pratt may be largely unfamiliar to UK TV audiences but they featured in a string of US shows after first finding fame in MTV show The Hills.

Show bosses were making life hard for some of the contestants with half due to be spending their time in a grotty basement area, while the others live in the more luxurious space in the house proper.

The series of Celebrity Big Brother is the fourth to be screened by Channel 5 in the space of 18 months, after resurrecting the show which had been dumped by Channel 4.

Casting bosses appear to have followed a similar format to the series this time last year which also roped in an X Factor star just weeks after they were in the ITV talent show, Frankie Cocozza. That series similarly saw appearances from a former EastEnder and a page three girl.

Ratings have been much reduced for the programme since it left Channel 4. The most recent CBB series which finished in September and was won by Julian Clary drew an average of just 2.3 million viewers, the lowest audience yet.

It was almost three million down on the 5.2 million average audience for the first ever series in March 2001.

PA