Speaking to The Sun On Sunday, the 38-year old reveals she was invited back to Cowell’s sprawling Holland Park mansion after crossing paths with the music mogul, 57, at the annual Comedy Awards.
Recalling the moment she entered his palatial home, Katie admits to being unsure if he was still in a relationship with TV presenter Terri Seymour – with whom he separated in 2008 – after seeing her belongings scattered about the property, Daily Mail reports.
‘We kissed. I got undressed and we got into bed together,’ she revealed. ‘His bedclothes were all white. He had a really hairy chest and I got this real sense of being with a man for the first time. He was the oldest person I had been in bed with.’
The Loose Women panellist, now happily married to third husband Kieran Hayler, admits that while she enjoyed herself with The X Factor judge they did not have full sex because of her reluctance to engage in meaningless one-night stands.
‘It was something my mum drummed into me from an early age,’ she said. ‘”If a man wants you he’ll wait for you.”’
Katie was already friends with record label boss Cowell having first met him as a shy, 17-year old aspiring singer through her then-manager, Harvey Smith.
That meeting would lead to a ‘confusing’ twenty-year friendship, during which they would infrequently drift in and out of one-another’s lives - culminating in their night at his mansion.
Looking back, she believes he had an ulterior motive after surprising her with a congratulatory call following her second appearance on endurance based reality show I'm A Celebrity... Get me Out Of Here!
'Perhaps he was concerned to I would reveal how intimate we had been?' she said. 'It felt as if he wanted to keep me separate from his public profile. I sensed he liked me but never involved me.'