A COLD War bunker, designed to withstand a direct hit by a nuclear bomb and built less than 20 years ago, has received one of the highest categories of listing in English Heritage s register of buildings of architectural and historic importance. But the 1

A COLD War bunker, designed to withstand a direct hit by a nuclear bomb and built less than 20 years ago, has received one of the highest categories of listing in English Heritage's register of buildings of architectural and historic importance.

But the 17th century riverside inn, the Pike and Eel in Needingworth, has been de-listed because of the quality and size of 20th century additions.

The "Magic Mountain", as the former US Air Force avionics building at RAF Alconbury is known to planners, was one of the last of a number of hardened structures designed to protect U2 and TR-1 spy planes at the base.

Built in around 1989, the building was used to service electronic components of the reconnaissance aircraft and process the data. It included life-support systems, decontamination rooms - including a facility for sterilising vehicles - workshops and darkrooms, protected internally by subterranean portcullis blast doors.

The lower floor housed the computers. A rare feature for maintaining air pressure in case of attack by the use of compressed air cylinders is still there. But nearly everything else has been removed.

A report by the Department for Culture, Media and Sport, which was responsible for listings until English Heritage took over last year, said: "The avionics building is unique among the few such buildings in England, because of its size, form and internal survival of the vehicular decontamination unit and compressed air re-pressurising system. It is uniquely associated with the U2/TR-1 aircraft, stationed only at Alconbury."

Louise Brown, head of Huntingdonshire District Council's conservation team, which is responsible for listed buildings, told The Hunts Post: "The Magic Mountain is very difficult for us because it's subterranean and designed to withstand a direct hit from a nuclear bomb.

"The structures at Alconbury [the World War II control tower is also listed] will be a problem to look after. But we can call on specialist advice when we don't have the expertise within our own team.

"It's unique in the world and extremely important in our history."

English Heritage believed the building was at serious risk of demolition to make way for re-development. It is the largest and most sophisticated of the three buildings of its type in England.

Flying at Alconbury ceased in 1995. The Grade II* listing - which makes the building only slightly less important historically than Grade I buildings such as the old bridge in St Ives and among the top five per cent most important buildings in the country - will severely restrict what the developers would be allowed to do with the site.

The Magic Mountain is currently earmarked for use by Cambridgeshire County Council in case of a civil emergency.

The Pike and Eel, at the end of Overcote Lane, Needingworth, was listed in 1982, along with every other pre-18th century building in the district, simply because of its age.

But English Heritage has decided that, in spite of its merits as a modest 17th century "vernacular" building, it had suffered considerable loss of fabric because of alterations and extensions that had compromised its "integrity and special qualities".

Although it had kept its local historical interest, it no longer merited inclusion on the statutory list of historic buildings.

Mrs Brown said: "The special interest of this building had been significantly eroded by numerous extensions and alterations, and it no longer met the criteria for inclusion on the list."

INFORMATION: Huntingdonshire has around 2,300 listed buildings. Nationally there are some 370,000 structures protected by listing, more than 92 per cent of them Grade II.

Grade I buildings are those of exceptional interest, Grade II*, such as the magic mountain, are particularly important buildings of more than special interest. Grade II are of special interest, warranting every effort to preserve them. Post-1945 buildings have to be exceptionally important to be listed. Buildings less than 30 years old are rarely listed, unless they are of outstanding quality and under threat.