From a Guardian article about Stonehenge quoted on the Portal -
" In the late 1980s a road to some proposed new visitor centre cut across an officer's vegetable patch at Larkhill Barracks. The ministry instantly declared the patch vital to national security. The Army Board even took the matter to Downing Street and a meeting with Margaret Thatcher. When she furiously overruled it, the board marked her order "urgent" and threw it in the bin."