Big Brother: Secret mission failed!

Big Brother housemates Mario, Lisa, Stephanie and Luke will all face the public vote this week after failing to pass their secret mission.

The quartet had been attempting to convince their fellow housemates that Mario and Stephanie were in fact a couple - when in fact Lisa is Mario's girlfriend - and the plot thickened further when Mario was ordered to propose to Stephanie.

The not-so-happy couple took part in a wedding ceremony in the house on Sunday afternoon, which went ahead despite the other housemates voicing doubts.

When the appointed minister asked whether anybody objected to the marriage, Alexandra - who had been telling the others she thought the whole thing was a Big Brother task - quickly spoke up.

"I think we all know how I feel," she said. "I contest. I feel this is a sham. It's been given to us in a task format. I don't think this is a strong enough bond. It's a sham."

However the minister quickly rebuffed her. "I appreciate your concerns, but that is not a lawful impediment to this marriage," she was told.

However, as they were being treated to a lavish reception and party, Big Brother finally confessed that there was in fact a secret couple in the house - and told the housemates they had one minute to guess who it was.

And almost immediately they correctly guessed that Mario and Lisa were in fact the actual couple - thus winning themselves immunity from eviction for the next week and leaving the unfortunate foursome to face the public vote.