Sienna's bee-line for Orlando

For a girl looking to punish her errant fiancè, it was a heaven- sent opportunity.

Sienna Miller arrived at the Cartier International polo event still furious with Jude Law for cheating on her with his children's nanny.

And who should be there but her old flame, the movie star Orlando Bloom?

Miss Miller, 23, made a bee-line for 28-year-old Bloom, a major Hollywood player thanks to roles in global blockbusters such as The Lord of the Rings and Pirates of the Caribbean.

Gazing adoringly into his eyes - are you watching, Jude? - she draped herself over him and kissed him passionately. The pair - who had a torrid affair back in 2001 when they were both unknowns - spent the afternoon laughing and flirting outrageously with each other in the Cartier marquee at Sunday's event, held at Smith's Lawn, Windsor.

As night fell, Sienna suggested that they adjourn to a private VIP section of the marquee run by the Mayfair nightclub Chinawhite.

A clearly flustered Bloom raced off to the lavatories, where he spent 15 minutes preening his hair and testing his breath in front of the mirror. He and Miss Miller then drank champagne together until midnight. 'They looked like a loved-up couple,' said a fellow reveller.

'Sienna had her arm round Orlando most of the night. They sat with their legs entwined, whispering in each other's ears and giggling.

They looked very much an item, but they left separately.'

Officially, Miss Miller remains betrothed to 32-yearold Law, who a week ago made a grovelling apology for a monthlong dalliance with nanny Daisy Wright.

But she has moved out of the London home they shared and dispensed with her engagement ring, saying she wishes to concentrate on her acting career.

Another object of her attentions on Sunday was Prince Harry, relaxing after leading his team to victory in the polo.

Sienna stopped first to chat to some of his school chums as the prince tried not to catch her gaze - presumably conscious of how his girlfriend Chelsy Davy, currently back at university in South Africa, might take the news of him being seen chatting to such a pretty girl.