John Travolta and Kelly Preston surprise Scientology party

John Travolta and Kelly Preston were the surprise guests at a Scientology event in England.

The Hollywood couple – who are still mourning the death of their 16-year-old son Jett, who tragically died in January – made a rare public appearance at the 25th anniversary of the International Association of Scientologists at Saint Hill Manor in East Grinstead, West Sussex, last weekend.

John and Kelly were joined at the event by fellow followers Tom Cruise and Katie Holmes and their three-year-old daughter Suri.

While John and Kelly remained quiet throughout the event, Tom – who is one of the sci-fi cult's most famous supporters – was very involved, especially when a choir took to the stage.

An onlooker told Us Weekly magazine: "Tom was swaying and looked like he was in heaven. He was really, really into it. Katie was next to him doing her best to look as enthusiastic. She was clapping along with the song, but was totally out of sync. Suri was standing by, looking a little bemused in a cute little party dress.

"John and Kelly were holding hands throughout the performance. They look like a very united couple."

Tom also gave a speech to the 4,000 guests, praising them for being part of the controversial religion.

He told the crowd: "Because we never took our eyes off the ultimate prize, we stand where we are today. We are in this together!"