Introduction

Historic England is the government's statutory adviser on the historic environment in England.It undertakes applied research to support the protection of the most significant historic sites in England.This research is often directed at filling knowledge gaps about particular types of buildings and over the last decades,a number of projects have addressed topics of 20th century industrial heritage,such as the effect of the motor car on England's architecture and landscape(Morrison and Minnis,2012).Strategies have also been developed to assess groups of buildings and places which are undergoing profound changes,such as post-war coal-fired power stations whose futures might be threatened,but where physical preservation is unlikely.Increasingly,more emphasis is being given to places where the historic environment might be used as a catalyst for economic regeneration.

In November,1989,the unexpected and initially confused opening of the border crossings through the Berlin Wall dramatically marked the final unravelling of the communist regimes in Eastern Europe.This culminated on 25 December,1991,with the dissolution of the Union of Soviet Socialist Republics,the United Kingdom's main adversary for over forty years.In the following years radical reappraisals of national defence policies were carried out by countries on either side of the former Cold War divide.To comply with treaty obligations many modern weapon systems and associated deployment sites were demolished.The perceived decrease in the military threat also led to massive reductions in the numbers of defence personnel and the scrapping of equipment.Accompanying these decreases huge areas of defence land were released,such as training and testing ranges,airfields,barracks and many other types of military establishments.

In England,closures included obviously historic sites dating back to the 17th century,including the Royal Arsenal,Woolwich and the Royal Gunpowder Mills at Waltham Abbey,Essex,and from later 18th and 19th centuries sections of naval dockyards and army barracks.In addition to these earlier sites,many hundreds of sites from the 20th century were also marked for disposal.These included airfields covering hundreds of hectares;many of which had been occupied by units of the United States Air Force and recently modernised.Throughout most of the Cold War designated civil regional government headquarters in protected bunkers and other facilities had been held in readiness across the country,along with systems to verify where nuclear attacks had taken place and stockpiles of food,emergency equipment and raw materials.This infrastructure was also stood down.(https://www.daowen.com)

Until their disposal,access to most of these places had been restricted and information about their activities closely guarded.Together they represented large areas of England and many thousands of buildings where historic records and understanding of their significance was lacking.At first work was focused on securing a largely photographic record of the establishments that were to be sold.Basic documentation was compiled for the National Monuments Record,now the Historic England Archive,and more detailed reports prepared on selected sites.

The years following the end of the Cold War also coincided with many fiftieth anniversaries of events associated with the Second World War and the beginning of academic interest in the archaeology and heritage of the remains of modern conflict.From the mid-1990s,Historic England and its predecessors initiated a number of projects to systematically identify and classify 20th century defence sites with a view to protecting the most significant.