Wills paid £200 for Kate to be his 'slave': Former housemate reveals couple's university chemistry

She first captivated her prince when she strutted down the catwalk in a sheer dress.

Or so the story goes.

In reality, Kate Middleton had won Prince William’s affections months earlier when he paid £200 for her during a ‘slave’ auction at a Harry Potter-themed party.

Lady-in-waiting: Kate Middleton as a first-year student at St Salvator's Hall at St Andrews - Prince William reportedly paid £200 her to be his 'slave' in a charity auction

The fascinating new insight into the early days of the royal romance comes from a former housemate of the couple, who is releasing a song about her memories of the pair as students.

Laura Warshauer lived with the new Duke and Duchess of Cambridge in St Salvator’s Hall during their first year at St Andrews University, and watched them fall in love.

Her song – titled To Will and Kate, Meet Me at Exit 109 – paints a picture of a fun-loving couple who joined in with a huge foam fight in the quad, drank wine out of plastic cups from Woolworth’s and sat on the floor to eat lasagne with fellow students.

Los Angeles-based Miss Warshauer also revealed how the couple had instant chemistry and had fallen for each other months before the now well-documented fashion show in March 2002 when William saw Kate modelling a see-through slip and described her as ‘hot’.

Miss Warshauer said: ‘One of my favourite memories was in November of [first] year and we were invited to a Harry Potter party at this castle.

‘We all got on a big bus to go there and I remember Kate and William dancing together all night.

‘There was a charity auction where you could bid for the person for the day and Will paid £200 for Kate. She was dressed in school uniform and was stood on these stone steps with us all below.

‘No one else was winning Kate that night. They already had that connection.’

Student digs: Kate, in a pink top, eats lasagne from a paper plate on her lap

Young couple: Prince William and Kate Middleton in snaps from their time at St Andrews

Kate and Laura Warshaeur as students - Laura lived with the future Duke and Duchess of Cambridge at St Andrews University

She added that all their friends expected the pair to end up together. ‘They always had such natural chemistry and it was obvious that Will had his eye on Kate,’ she said.

‘I remember a college party with Will and Kate very early on during freshman year.

‘A girl went over to Will and wouldn’t leave him alone. She was trying to entice him, and was being relentless. He was being very polite to her, but at the same time, it was obvious he wished she would leave him alone.

‘A group of us were standing around watching all this unfold and wondering how to help Will out of this awkward situation.

‘Suddenly, Kate just walked up to Will in the most natural way and put her arms around him.

‘It gave Will the opportunity to turn to the other girl and say, “I’m sorry, I have a girlfriend,” while gesturing towards Kate.

‘Will then turned to Kate and mouthed in an exaggerated way, “Thank you”. She was the only girl in the room who could have pulled that off so effortlessly.’

Prince William and Laura Warshauer pose for a photograph during their St Andrews days

The music video shows several pictures of Miss Warshauer with the couple, and the track includes the lyrics: ‘Here’s to Will and Kate, on your wedding day. I remember living in the freshman dorm with you.

‘Paper plates and plastic forks we sat on the floor, drinking wine out of plastic cups from Woolworths.’

The ‘Exit 109’ in the title refers to where she grew up in New Jersey.

The 27-year-old insists she is not cashing in on her friends and simply writes about ‘special memories’.

She said: ‘They are both such incredibly warm, down-to-earth people who genuinely care about others.

‘One night I was little upset about something, and Kate so sweetly put her arm around my shoulders, asked what was wrong and said “I hate seeing people I care about upset”.

‘We drifted apart like so many students after I returned home to go to New York University, but I would love to meet up again one day.’

Miss Warshauer’s single is out now on iTunes. Her album, The Pink Chariot Mixtape, will be released on June 14.

In line to the throne: Kate with friends at her halls of residence