The boy who cast a spell on Hermione

The 17-year-old actress feared her feisty portrayal of Hermione Granger in the Harry Potter films might have intimidated potential suitors.

But last week, Emma's fears seemed unfounded as she enjoyed a magical time on the French Riviera under the spell of handsome young rugby player Tom Ducker.

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Magical time: Emma with Tom in Nice last week

The teenagers were spotted hanging out in nightclubs and eating lobster with £90 bottles of champagne in an expensive seafront restaurant.

Staff at their hotel, Chateau de la Chevre d'Or in Eze, near Nice – where suites with ocean views cost £385 a night – described Emma and Tom, who is also 17, as 'delightful guests'.

In the five years since the first Harry Potter film, Emma – like co-star Daniel Radcliffe – has accrued a fortune, estimated at £10 million.

But unlike Daniel, who insists he only buys things that cost about £10, such as books and DVDs, Emma appears much less prudent – at least when she is on holiday.

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Hermione and Tom: looking slightly more than just friends

Emma signs an autograph on the red carpet at the latest Harry Potter premiere

While sipping Veuve Clicquot in the Castel Plage restaurant on the famous Promenade des Anglais near Nice's old town, she was taken by some artwork, worth about £15,000, that was hanging on the wall – and offered the owner cash for it.

The work, entitled "Je suis incognito ici, faites le savoir" (I'm incognito here, tell everybody) is by renowned Italian artist Ben Vautier.

"Emma fell in love with it and offered to buy it there and then," said owner Ali Abdelhafidh. "The words on the piece seemed to sum up her evening. But sadly it just wasn't for sale, so she posed for a photo next to the picture instead."

He added: "They arrived quietly at about 7.30pm and drank champagne and ate lobsters all night. They were clearly loving each other's company and said they were in a very romantic place, with the Mediterranean just in front of them and great music.

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Emma relaxes off-screen with Tom Ducker (centre) and another girlfriend

Perhaps Hermione could teach Tom a thing or two about waistcoats

"They said they were having a wonderful holiday and did not leave until well after 2am. It was great to see a young couple so much in love but Emma had time for everyone else, too.

"A lot of celebrities come here, including Elton John and Bono, but having Emma here was something special. She's a real star in every sense of the word."

A fellow diner said: "They were knocking back the champagne and didn't stop laughing and joking. Emma was acting like a beautifully mannered young woman. Castel Plage is very sophisticated and the two of them looked in their element."

But back home in Chipping Norton, Oxfordshire, Tom's father John, 50, said: "They are just friends – don't read anything more into it than that. My wife and I have met Emma once or twice. She is a lovely young lady."

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Emma in a recent pose for Tatler magazine

The actress with the £15,000 artwork she hoped to buy

Emma met Tom, who has signed for Wasps, in Oxford where she lives. Like her, he is an academic high-flier, scoring near-perfect grades in his GCSEs last year.

Although Emma's parents have set up a trust fund to bank her riches until she is 21, she receives a monthly allowance believed to be well into four figures.

The couple told staff at Castel Plage that they would also be sampling the nightlife in nearby Cannes and St Tropez, before heading east to the Italian Riviera.

Emma, who was born in Paris and speaks good French, said she was "having a wonderful time" and glad to be away from the "Harry Potter madness back home".

Meanwhile, negotiations are under way to secure Emma, Daniel, and Rupert Grint, who plays Ron Weasley, in their roles for the final two instalments of the blockbuster series.

Emma has often hinted that she is uncertain about a commitment that will tie her up until she is 20, especially as her role left her little time for romance, despite being surrounded by hundreds of "cute guys working on the crew".

In a recent interview she said: "People say to me, 'It must be so easy for you. They must be lining up for you.' It's not easy. It's a minefield. Really. It's stressful."

But, perhaps, not any more.