Her onscreen character, the famously uptight Hermione Granger, would almost certainly have disapproved.

But Harry Potter actress Emma Watson proved she is a far freer spirit as she partied at society event Cartier Polo. And there was no shortage of male admirers to help the 18-year-old star enjoy the occasion.

Dance with a Granger: Emma Watson partying with actor Roberto Agnillera

Among them was a fellow actor by the name Roberto Agnillera. Miss Watson invited
the young Italian to join her at the event after they met recently at RADA.

The couple sat in the royal box to watch the 24th Cartier Polo match at Smith's Lawn in Windsor before retiring to the dance tent.

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Tete a tete: In conversation with Francis Boulle

By the end of the night they were dancing on the podium together, her arm draped around him in a gesture of intimacy.

But he did not monopolise Miss Watson's attentions.

Francis Boulle, 19, a Franco- Mauritian philosophy student at Edinburgh University, was seated next to her over lunch and was seen swapping phone numbers later in the evening after spending an hour in intense conversation.

Dancing partner: Emma Watson dances with her male companion to the sounds of DJ Mark Ronson

He said: 'She was very sweet and we had a lot in common.'

Also seen deep in conversation with Miss Watson was blond-haired Michael Walker, 18, who is waiting to find out if he has won a place at Cambridge after sitting his A-levels at Eton.

Bonding with a blond: She chats to Michael Walker

Her affectionate behaviour is unlikely to please her steady boyfriend, 25-year-old financier Jay Barrymore, who is away on holiday.

Miss Watson, who split from her first boyfriend, Tom Ducker, 17, last year, has just completed filming the sixth instalment of Harry Potter.

She has decided to study Shakespeare at RADA, having finished her A-levels.

Making eyes at each other: A champagne-swilling Emma gives her companion Francis Boulle a knowing look

Eye to eye: Emma Watson gets close to Francis Boulle

Arriving in style: Emma Watson, dressed in sheer Charles Anastase dress, was well prepared for the sunny temperatures