The polished showrooms of Blickling Hall are hailed as national treasures. But behind the scenes, there's a whole other world hiding behind the grandeur. STACIA BRIGGS take a backstage tour, from the below-deck tunnels to its lofty turrets.

Blickling Hall is preparing to unveil some of its hidden secrets this month, from a servant's tunnel which burrows under the hall's moat to an attic filled with echoes from the past.

During weekends in November, parts of the historic hall which are usually out-of-bounds to the public will be accessible on special tours being led by some of the hall's army of 400 volunteers.

Visitors will be able to take a tour of the private rooms usually hidden behind rope barriers, the extensive attics and visit what was once the heart of the hall – the boiler room and coal store.

House manager Jan Brookes-Bullen hopes the behind-the-scenes tours will give visitors the chance to see the continuing work at the hall, restoration projects and a treasure trove of relics from a bygone era.

She explained that every 'backstage' tour would be different, depending on the tour guide, the size of the visiting group and the mobility of individuals.

From the opulent Great Hall, with its grand staircase, jewel-like stained glass and much remarked-upon relief of former resident Anne Boleyn, we walk down a corridor which leads to a trio of conference suites, the Blue Drawing Room, Garden Room and Lord Lothian's Study.

Events such as weddings and parties are held in these splendid rooms which all overlook the hall's meticulously-maintained gardens.

Books belonging to Lord Lothian, whose family bequeathed Blickling Hall to the National Trust in 1940, line his study, forming the 'day-to-day' segment of the hall's library, which is said to be one of the most impressive collections of books in Britain.

From the study, we walk along the Stone Corridor, past the modern kitchens installed for catering and towards the tunnel and the old boiler house. The temperature dips sharply.

'There's another life within the National Trust, and it's one that people don't always see. The hall is a business which has to pay its way, but the visitors rarely get to see beyond what we call the 'show rooms' and to the work that goes on behind closed doors,' she explained.

Just beyond the corridor is a room with a fine tiled floor and leaded windows which, excitingly, leads to a tunnel which passes under Blickling Hall's moat and was once used by servants to ferry food from the kitchens to the main hall.

Taken out of use in Lord Lothian's time as lord of the manor, until recently the tunnel and adjacent room were plagued by flooding problems which have left behind a legacy of mildew.

After extensive cleaning of the pipework under the moat, the tunnel no longer floods and, Ms Brookes-Bullen hopes, will be open to the public in the future.

Next is the boiler house, a remarkably small, brick-lined room housing a large, redundant, 19th century boiler and, by its side, an even smaller room where coal was once piled to the ceiling to provide fuel for the hall's 40 or so fireplaces.

'I hope that this is an area we can also open up in the future. It needs to be made safe for visitors, but we wouldn't decorate – people like to see the historic surfaces and feel the history for themselves, rather than have it spelled out to them,' she said.

'When Lord Lothian spent weekends at Blickling, he expected 20 of the 40 fireplaces to be lit because these huge country houses can get very, very cold. The trip to the coal store would have been one that was made very regularly!'

We move on to the Brown Staircase, currently supported by a wooden structural support, but shortly to be unveiled after load-bearing tests revealed the stairs can withstand the weight of visitors. A beautiful blend of metal and mahogany, the stairs are often mistaken as 'servants' stairs', but were actually also used by the families living in the hall, too.

Ms Brookes-Bullen explained that the stairwell would soon be repainted in a historically-accurate shade of cream, following a painstaking procedure involving paint-scraping of the wall, microscopic investigation and expert paint-blending.

Paintings from the stairs are being stored in the soon-to-be-opened exhibitions room, just off the staircase, which will showcase ongoing restoration work at the hall and offer visitors a chance to see the hard work that goes into keeping Blickling's finery in peak condition.

The exhibition room is due to open in February, but will be included on the backstage tour.

As we climb the Brown Stairs to the Buckingham Row Landing, the sheer scale of Blickling Hall is apparent – this is just one wing, and the attic space is awe-inspiringly huge. Room after room open out from a corridor, each packed with a treasure trove of incredible objects.

'The attics are where we store all the items that can't be used as part of the Blickling collection because they are too old, too worn out or are awaiting restoration,' she said.

Inside the attic rooms, the canvas-lined walls are showing their age. Wallpaper is peeling and there are patches of mildew, but there is still a sense of faded grandeur and, of course, spectacular views of Blickling's distinctive brickwork chimneys, sweeping driveway and splendid gardens.

These are the rooms where servants once lived ('the lower down the social scale you were, the higher you lived!') or where guests would stay. Today, they entertain the relics of the hall's past – there are shelves of ceramics shrouded in protective foam, rows of picture frames and mouldings, piles of textiles, a library of books and the sheeted, ghost-like remains of furniture too delicate to remain in the hall.

At the end of the corridor, past a set of servants' bells, is Flo Wadlow's room, currently being restored to echo how it used to look when Flo worked as a cook at the hall in the 1930s.

Now in her 90s, Flo has assisted with the restoration of her room and will help open it to the public in a matter of months to give them a glimpse into what used to be her day-to-day life.

n Backstage pass tours will be held at Blickling on weekends throughout November from 1.30pm to 2.30pm on Saturdays and Sundays, �5. Spaces are limited, pre-book on 0844 8004308.

www.nationaltrust.org.uk