Ray hopes he can relax inside the house

On Monday night ratings had dropped to just 3.2m viewers, down from a high on launch night of more than seven million viewers.

The ratings are down 800,000 on the corresponding show last year and come despite the channel populating the house with younger contestants.

The figures will lead to speculation that Channel 4's cash cow series has run its course, after three hugely successful series which captured the public's imagination and led to a rash of imitators.

Twelve contestants, with an average age of 25, entered the Big Brother house last Friday and will spend up to nine weeks locked away from the outside world with their every movement tracked by cameras and microphones.

The viewing public will vote to evict contestants until one person is left, winning �70,000 in prize money and possible fame.

Dwindle

The three previous winners on the programme, Craig Phillips, Brian Dowling and Kate Lawler, have all found a measure of success on TV and radio since they emerged victorious.

Channel 4 will be hoping that interest in the programme rises as numbers in the house dwindle.

Last year, more than nine million viewers turned in to see 22-year-old IT worker Kate Lawler, from south London, win the contest.

Big Brother, first shown in Holland in 1999, has become a worldwide hit, broadcast in 22 countries.