THEY are siblings in real life, but four children are also acting as siblings in a film featuring Life on Mars and Dr Who star John Simm and actress Shirley Henderson, of Trainspotting and Harry Potter fame.

THEY are siblings in real life, but four children are also acting as siblings in a film featuring Life on Mars and Dr Who star John Simm and actress Shirley Henderson, of Trainspotting and Harry Potter fame.

The four Kirk children will not see the end product of their work until 2012, but for now they are happy with the dual rewards of an enjoyable experience and lots of sweets.

Internationally-famous director Michael Winterbottom, the man behind crime series Cracker and films such as Jude, 24 Hour Party People, 9 Songs and A Cock and Bull Story, is in the process of making a Channel 4 film called Seven Days.

The film, unusual in that it is being put together in short stints over a five-year period and is not due

to be released for another four years, charts the relationship between a

man imprisoned for drug-smuggling, played by Simm, his wife, played by Henderson, and their four children.

Those children are Stephanie, aged nine, Robert, seven, Shaun, five, and Katrina, four, all the children of Norfolk couple Colin and Sarah Kirk. The family lives near Fakenham.

Stephanie said: “I am very pleased to have been given the chance to act in this film.

“The crew like to make us laugh and play. I am looking forward to the next lot of filming because they always bring us lots of sweets.”

The cast were in Norfolk last week and spent part of their time at Cromer High School, and other locations around the county.

Mum Sarah said the family's involvement started more than a year ago when Shaun was picked for a part in the film because he looked similar to John Simm. The crew came to the house to film Shaun and when they realised he had three brothers and sisters all were asked to take part.

“The kids are naturals; we never imagined they could do this kind of thing, but they love it and they are extremely comfortable with what Michael asks them to do. And he is a natural with them too, so it works very well,” said Mrs Kirk.

Mr Winterbottom said the film was being shot over such a long period of time to help bring reality to the ages of the children as they grow up.