Some of the movie was shot at Holkham Hall over two weeks in October 2007, and went on general release last September.

The clothes are now on display until the end of August each Sunday, Monday, Tuesday and Thursday from noon until 4pm.

London costume company, Cosprop, has provided the faithfully-reproduced clothes which were worn in scenes shot in Holkham Hall's sumptuous salon – a grand setting with walls lined with the oil paintings of masters including Rubens, Van Dyck, Chiari and Carlo Maratti.

Costume designer Michael O'Connor won an Oscar for his colourful clothes which accurately evoke the 18th century, in which the story was set.

"All the costumes are absolutely period correct, but we used fabric that is new. We also used lace, trims and buttons from antique fairs and markets," said Christine McSweeney, Cosprop's exhibitions co-ordinator.

"Michael drew the designs from which were made the patterns and the clothes were then fitted on the actors."

This personal fitting was partly done because it was necessary to ensure the colours complemented the skin tones of each individual actor.

The passion for accuracy even extended to some of the actors having to be sewn into their costumes before each day's shooting, to make sure their shape was absolutely authentic.

The underwear, though obviously not seen, was also designed to match exactly that worn at the time. For Keira Knightley this included tight corsets and hidden panniers to make her hips look very wide and her waist very slim – the shape that was all the rage when the duchess was young.

In later years, the look was slimmer and 'bum rolls' for the women and bottom pads for men came more into fashion.

These hidden constrictions, made just as carefully and accurately as the outside garments, ensured that the movements of the 21st century actors would more accurately reflect the way their forebears moved more than two centuries ago.

Cosprop employs some 20 seamstresses.

"They are all very clever," said Mrs McSweeney. "Although we use sewing machines there is also much expert hand-stitching done in the way it would have been done in that period, to give the clothes the right feel and look."

The story of the film concerns the real- life Georgiana Spencer (Keira Knightley), an ancestor of both Princess Diana and Sarah, Duchess of York, who marries the fifth Duke of Devonshire (Ralph Fiennes), only to be trapped in a loveless marriage because all her husband wants is a male heir.

He has several affairs and Georgiana herself falls in love with young nobleman, Charles Grey (Dominic Cooper).

In a story, which also involves politics and her heavy liking for gambling, she is finally forced to return to the Duke under threat of never seeing her children again.

Georgiana's real life was one long social whirl and the scandal of the age.