The documentary photographer Richard Smith has become increasingly concerned about how human activity is affecting and changing the landscape. The Upper Heyford air base, on 1,200 acres of Oxfordshire, is a case in point. So in 2008/09 he negotiated access. What he found is recorded in this show.

Upper Heyford was for 40 years a USAF base, up until 1994. English Heritage has described it as one of the most important Cold War sites in Europe and is keen to see it awarded protected status.

It was home to an air corps of nuclear-armed long-range bombers, and older residents of Steeple Aston, Ardley, Fritwell and the Heyfords will recall the sound of the jet engines on standby and the overwhelming noise-rush of take-off and landing.

But given its top-secret status few locals ever penetrated the site. What Smith found, when he did, more than 25 years later, was tired, disused and in parts ramshackle. But it had nevertheless retained the heart and soul of a war machine.

The exhibition is dominated by a large photograph shot through wire fencing where sheep are grazing rather forlornly over the top of an underground bunker. Another documents the serried ranks of aircraft hangars, while still more focus on a single hangar, closed and out of action or open and ready for strike. Meanwhile the disused control tower (pictured) retains an operational alertness.

The whole serves to remind us that in the heart of our peaceful countryside there was a military presence with global significance and the potential to impact for ever on our green and pleasant land: an impact that Smith captures well.

The exhibition is at the Said Business School. It is open daily, subject to the school’s other commitments and it continues until March 30.