Hollywood star John Travolta wowed guests at a charity ball when he performed an impromptu Grease-style dance with his wife

The usually private actor, famed for his dancing roles in movies such as Saturday Night Fever, leapt from his seat at the event in West Sussex and joined soul singer Isaac Hayes on stage.

Thousands of people who packed into a giant marquee at the UK base of the Church of Scientology in East Grinstead hoping just to catch a glimpse of the Pulp Fiction star danced along in disbelief.

Travolta and his wife, Kelly Preston, took centre stage on a raised podium to dance to the soul classic Stand By Me.

Other performers flown in for the fundraising event at the church's fairytale castle, including Broadway singer James Barber, musician Mark Isham and female vocalist Elena Roggero, also flooded back on to the stage for the finale.

Organisers of the event, the International Association of Scientologists, said Travolta - who pilots his own jetliners - had flown in especially for the gala ball, and was expected to leave today.

During the concert, cheques were presented to a number of UK charities including Age Concern, the Royal Commonwealth Society, who made Scientology founder L Ron Hubbard a life-long member, and the City of London Police's charity City Kids, designed to support inner-city children and those affected by the July 7 bombings.

Travolta and his wife then took to the stage with concert host, Patriot Games actress Anne Archer, to present a £40,000 cheque to the Sheriff of New Orleans, Harry Lee.

The Face Off star and Ms Preston joined other Scientology ministers to help the police in the US city in the aftermath of Hurricane Katrina.

Travolta said: "The police officers and their relatives working in New Orleans at that time suffered the same losses as everyone else."

Sheriff Lee said to the concert audience: "After Katrina, I was up to my elbows in alligators and looked up and there was John and Kelly. Not eight weeks later, here I am 10,000 miles away in a room full of the most committed people I have ever met and there's John and Kelly again."

Travolta, who received a standing ovation as he walked into the marquee, is a firm supporter of the Church of Scientology along with fellow Hollywood legend Tom Cruise.