At first glance the groups of ballgown and tuxedo-clad revellers looked like any other ball or prom in Oxfordshire.

But on closer inspection, cameras, lights and a megaphone-wielding director suggested otherwise.

People from across the county donned their party finery to act as extras in a film adaptation of Philip Pullman's book, The Butterfly Tattoo.

Filming of the project, expected to be released at Cannes Film Festival in May, finished at the weekend.

And more than 150 people answered a call to take part in the filming of one of its biggest scenes - a masquerade ball at Howbery Park, near Wallingford.

Among those searching out their best dresses for Friday's shoot, were Nonie Cockburn, 16, Lucy Walters, Josie Van-Es and Lucy Bale - all 15-year-old pupils at The Cherwell School in North Oxford.

Josie said: "We thought it would be a really good experience. It's really exciting. We were running around all day trying to get dresses, then we realised our parents had long dresses so we borrowed those."

Lucy Bale said: "It's different being in front of the camera. It's not just the performing that's exciting but seeing everyone getting ready.

"I really am looking forward to seeing myself in the film. I was in another scene too, so I'm going to be saying 'wow, it's me!'"

Tom Goodwyn, 21, from Headington, said: "I've never done anything like this before so I thought I'd give it a try.

"It's all very strange. There are lots of people running about. The best part will be seeing it on the big screen."

Drama student Hannah Feldman, 17, from Horspath, near Oxford, and a student at Wheatley Park School, was hoping the experience would give her an insight into the world of cinema.

She said: "It sounded really good and I couldn't wait to be on a real film set. It seems very well organised.

"We are definitely going to be watching out for it. It's really cool."

Schoolfriend Louise Parish, 17 from Garsington, added: "It will be really interesting to see myself on film."

Producers have been filming around Oxford for the past six weeks.

Among the city locations used was the Martyrs' Memorial, Cowley Road and Walton Street rock venue, the Jericho Tavern.

Producer Wesley Kloppenburg said: "It's been great.

"The whole thing has gone better than I expected, and it's going to be fantastic."

Mr Kloppenburg came prepared to make a cameo appearance in the ballroom scenes - bringing along his tuxedo for the occasion.