He famously performed a karaoke version of the song at his cousin Zara’s wedding reception – but it seems that was merely Prince William’s warm-up.

To the delight of the 600-strong audience at a charity event, the future king was persuaded to join Jon Bon Jovi on stage to sing along with his band’s hit Livin’ On A Prayer.

American star Taylor Swift made up the third member of the rather unlikely trio as they gave the impromptu performance, which even featured the Duke of Cambridge playing the air guitar and ended with him high-fiving his bandmates.

The spectacle was the finale to the glitzy Winter Whites Gala evening at Kensington Palace on Tuesday which raised more than £1million for youth homeless organisation Centrepoint.

Aides insisted William’s stunt had not been planned in advance, with one saying: ‘It was totally off-the-cuff. None of us could believe our eyes.

Video of the royal singing with Miss Swift and Bon Jovi – whose music William’s late mother loved – has already become an internet sensation, with hundreds of thousands of views.

Perhaps they include his wife Kate, who missed the show to look after their four-month-old son George.

The performance took place inside a specially erected marquee for a concert compared by Jonathan Ross and kicked off by Eliza Dolittle, who thanked Prince William for 'letting us use his gaff tonight’!

Other acts included James Blunt and rapper Tinie Tempah, who adapted the words of his hit single Children Of The Sun to include a reference to Prince Harry’s notorious Las Vegas antics.

Star turn Taylor Swift electrified the audience with a performance of her hit singles Trouble and Fifteen.

She told the audience: ‘I’m Taylor, it is very nice to meet you, especially under these circumstances. It is my first time playing at Kensington Palace or any other palace for that matter.

'I have to thank you, Prince William, for having me. It’s amazing.
'To call attention to this age group especially, teens and young adults.'

She also sang her breakthrough hit Love Story, written when she was banned from going on a date at 17.

She said: ‘This has reference to palaces, princes and princesses and it is very strange that I end up playing it in a palace.’

Speaking about performing at the gala earlier in the evening, Taylor said: 'I'm absolutely excited. I don't think I've ever played at a palace before, so it is really wonderful.'

It's safe to say that she hasn't belted out a Bon Jovi hit with a future king of England either - so it was a night of firsts for the 23-year-old singer.

The pop princess was wearing a Reem Acra dress and carrying a clutch bag by Jenny Packham, the same designer who made the blue and white polka dot maternity dress Kate wore when bringing baby George out of hospital.

Jon Bon Jovi said meeting the Duke had not been an intimidating experience, as he had already met most of William's family: 'I met his father and I met his grandfather. He's still a young kid to me, but a nice young kid.'

He added Prince George was the next generation for him to meet while saying he may try to convince William to get on stage.

William was known to have performed a karaoke version of Livin' On A Prayer at his cousin Zara Tindall’s wedding reception.

Guests paid at least £500 each to attend The Winter Whites Gala, which was held in aid of Centrepoint, a charity for youth homelessness.

The Duchess of Cambridge missed the event, kept busy looking after four-month-old George in the couple's 20-room apartment next door.

The palace itself was decked out in the style of a winter wonderland, with fake snow, fir trees and icicles.

Prince William took to the stage at the end of the evening and couldn’t resist joking that he ‘felt a duet with Tinie Tempah coming on’, also quipping ‘that’s not the first time James Blunt has sung and dedicated Your Beautiful to me’.

But he stressed that despite the fun nature of the evening it was all about ‘those young people less fortunate than us, who, for reasons very often out of their own control, find themselves sleeping rough; not knowing where their next meal is coming from; without anyone to turn to; helpless.’

In a speech he said: ‘A few years ago at about this time of year, for one night only, I gave up the comfort of my bed and tried sleeping on the streets of London. That was just one night, and I knew I had a home waiting for me. Many others have no such comfort – the cold streets are the only reality they know.

‘After that night, the Chief Executive of Centrepoint, Seyi Obakin and I decided to set Centrepoint a very tough challenge: to end youth homelessness within a decade. We felt that this was an ambitious yet achievable goal, and one worth striving for. We are now several years into that decade, and Centrepoint has been working strenuously to achieve this ideal.

‘However, as I saw for myself last week when I visited a Centrepoint facility in Sunderland, the problems remain as acute as ever. Centrepoint knows it cannot succeed alone, which is why I am delighted to welcome so many here tonight who share with us the same ambition.

‘Tonight will move us all one step closer to helping these deserving young people, these inspiring young people who, given the right opportunities, can go on to achieve so much.

‘Our support, ladies and gentlemen, can allow them to secure themselves a bed, an education, a job, a future.

Earlier in the day William was at London Zoo with his father, Prince Charles, to see the new tiger enclosure.

William and Charles both have a passion for conservation, and were launching a new project to try to halt the illegal trade in endangered animal products.

Prince Charles said he wanted to highlight the worrying increase in the trafficking of ivory and rhino horn as well as bush meat and live endangered species.

The zoo has two Sumatran tigers, a five-year-old male called Jae Jae and his mate, Melati, five, big cats who face an uncertain future in the wild.

Describing them as ‘beautiful and majestic’ creatures, William spoke about the United for Wildlife project, of which he is president.

William spoke from the heart about his determination to get experts in ‘one room to focus their energy and their commitment to one cause - particularly obviously this illegal wildlife trade at the moment is such a big issue’.

‘The idea was that United For Wildlife can progress and we can really start the ball rolling and the momentum and really try and change and tackle this issue,’ he said.

The prince, who said he hopes to travel to Kenya next year to further his work, went on: ‘Education is the most important thing as we saw with the shark fin soup campaign - the more education, the more obviously we can put out there and show people and educate them on what they’re buying and what they’re seeing and really try and change their attitudes.'