The first thing to confront you as you enter the impressive entrance hall at Stokesay Court is an 8ft tall stone statue, sitting proudly and somewhat incongruously in the centre of a magnificent wood-panelled room, writes movie blogger Carl Jones.

At first glance, the God-like figure appears to be a precious masterpiece which has proudly stood guard over a century of secrets.

But wait . . . a quick rap of the knuckles on the chap’s nether regions unmasks him as an imposter. Nothing more than a hollow, lightweight, fibreglass fake.

Similar optical illusions lurk all around this majestic 19th-century country mansion.

What appears to be a weathered and worn stone arch in the garden grotto is actually a carefully sculpted piece of polystyrene, while several piles of 6ft tall strategically placed ‘boulders’ sit on the patio, and on closer inspection are revealed as far from genuine.

This is the legacy of Atonement, the Oscar-tipped movie which is currently riding high in the cinema box office charts, and which used the house at Onibury near Craven Arms as one of its key locations.

For four months last summer, film company Working Title brought a cast including Keira Knightley, James McAvoy, Vanessa Redgrave and Brenda Blethyn to Shropshire to film some of the movie’s pivotal scenes.

And this weekend, Stokesay Court’s owner Caroline Magnus leads the first in a series of new Atonement Tours, taking visitors to the usually private residence on a two-hour journey which unmasks some of the movie makers’ secrets ­ and reveals the lengths to which they would go to achieve on-screen perfection.

I’m on site for a sneak preview.

“This is the place where Keira Knightley and James McAvoy had their most intimate scene,” explains Caroline, showing us into the billiard room which the producers turned into a library for the scene ­ and kindly left the rows of bookshelves behind.

“Although they brought in their own props and I packed up my own furniture to put in storage while they were here, you will find evidence of the film’s sets in many of the rooms.

“When they had dressed them, with wall coverings and other small features, I was usually given the option of having them left behind for me if I liked them. It was about fifty­fifty ­ some looked perfect, but I wasn’t so keen on others.

“They’d decorated some of the passages a rather bilious green, for example, and painted a disgusting brown in the dining room. Those had to go.”
Much, however, has been left behind and will be instantly recognisable to anyone who has seen the movie.

The stone statue in the entrance hall, for example, was actually used to expand and enhance the fountain in Stokesay’s grounds ­ other remnants from these scenes are still around the fountain perimeter.

The silk wall coverings and seat fabric which the Atonement team used to add colour to the drawing room all remains intact and, on the first floor, those familiar with the film will recognise the wardrobe and mirror which Knightley used while dressing for dinner, as well as young Briony’s room where teen actress Saoirse Ronan filmed many of her scenes.

But it’s the nursery which, certainly for Atonement fans, is the jewel in the crown.

This has been entirely preserved, and is exactly how the movie makers left it, right down to the signs on the walls with comments to cast and crew like: “please do not touch ­ pain of death”, and “dressed set, no equipment please”.

Caroline has supplemented this with a display case containing a host of remnants from filming, including call sheets and even an offcut piece of the emerald green dress which Knightley wears, and you can gaze out of the window towards the fountain just as young Ronan does in the movie.

Even for non film fans, there’s much to recommend on a trip to Stokesay Court. It has a fascinating history ­ built by wealthy Victorian merchant John Derby-Allcroft between 1889 and 1892, used as a military hospital for convalescent soldiers during World War One, and occupied by Lancing College during World War Two when they were evacuated from Sussex.

Its contents were sold in a massive auction in 1994, and it was an article at that time in Country Life magazine, which the Atonement makers found while flicking through back copies, which alerted them to its suitability.

They not only loved the building, but found the grounds a perfect match for the adaptation of Ian McEwan’s complex novel of betrayal, romance and regret.

In the Atonement tour, guests will have time to explore the grounds, where they will find a secret garden grotto which played a crucial role in the film’s storyline, the beautiful weir where James McAvoy dived in to perform a dramatic rescue, and the picturesque tree-lined lakeside where Knightley and company filmed scenes around a sun-drenched diving board.

Gazing back towards the splendid building across the lawns as we make our return, it’s clear to see why the Atonement producers were won over by Stokesay Court. But Caroline points out an interesting quirk which I had completely overlooked.

“See the right-hand wing of the house over there,” she points. “In the film, it’s been completely airbrushed out of the shots. It’s as if it isn’t there.
“It s strange to see.”

Don’t let anyone tell you these days that the camera never lies.