The unlikely pair, who fell for each other in the Big Brother house, shared a steamy night of passion after Luke, 21, became the seventh evictee from the house the weekend before last.
The couple had their first night together on a four-poster bed in their £2,000-a-night luxury suite at a London hotel.
Confession: Luke Marsden has admitted sleeping with his fellow evictee Rebecca Shiner
Luke admitted: 'The only problem was the bed was so high I nearly fell off and broke my neck at different stages.'
He added: 'Rebecca and I first made love the night after the night I left the Big Brother house, and it was amazing.
We simply couldn't on my eviciton night because we needed to talk first and there was too much going on.
'But by Saturday at around 11pm, after a long day, we crawled into bed and just started kissing.
Close: Luke and Rebecca share a tender moment in the Big Brother house
We looked into each other's eyes and knew it was the right time. Without saying a word, we knew what was going to happen - it was inevitable.
'The setting was perfect - the lights were dim and Rebecca and I have never known such luxury - although it would have been nice to have some atmosphere - and no, I'm not talking about Kat or Darnell singing!'
The pair confessed they were so paranoid about being watched by the cameras, they kept expecting to be called into the Diary Room.
Rebecca, 21, said: 'We were so sure we were still being watched!
'We even checked. But eventually, we forgot about that and made up for lost time.'
