One of the three-man BRIXMIS teams, seen here spotting for Soviet Aircraft (Picture: BRIXMIS Association).
At the height of the Cold War, a small group of British, American and French soldiers spent their days driving into enemy territory and spying on Soviet forces.
They were the only Western forces to regularly get up close and personal with the enemy, but who were they? And how come their story is still so little known?
BRIXMIS, or the British Commander in Chief's Mission to the Soviet Forces, was created in the uncertainty that followed the end of the Second World War.
As the Allies who had defeated the Germans (America, Britain, France and Russia) sat around the table negotiating what victory should look like, it soon became apparent that liaison missions between the four countries would be desirable.
Germany itself was divided up into four different occupation zones.
In the East, roughly a third of the country would now be controlled by Russia and the remaining two-thirds in the West would come under American, British and French control.
The German capital, Berlin, was also split into East and West.
The border became literally set in stone in 1961 when the Communist-controlled East erected the Berlin Wall.
Mutual distrust and the constant fear of nuclear war led to the paranoia and suspicion of the Cold War years.
Throughout four decades, four military liaison missions were in operation, the American USMLM, the French FMLM, the Soviet SOXMIS and the British BRIXMIS.
The principle for all four was the same: the right to roam in East Germany for the Western Powers, and West Germany for their Soviet counterparts ostensibly as liaison functionaries between the powers so they could circumvent Governmental authority in a divided Germany.
However, all sides soon realised the vast potential for intelligence-gathering and spying.
"What we risked our lives and limbs for, to gather intelligence information all those years ago, now is all freely available," explains BRIXMIS veteran, Dave Butler.
"We were spying. They knew it and we knew they knew it. That was part of the game back then."
BRIXMIS was allocated 31 passes, which meant 31 members of personnel could travel in and out of East Germany in full uniform while driving marked cars.
The three-man teams would carry maps, stills cameras, dictaphones and latterly video cameras but they were all unarmed, relying on their wits to defend themselves when they crossed swords with Soviet troops or the East German secret police, the Stasi.
Each team took great care not to write anything down that could incriminate them.
They were always very conscious any moment the vehicle could be rammed, or "turned over".
The only things they marked on their maps were safe places to set up camp for the night with a little Z, and places to stop for an ice-cream when they got hot.
It was these little ice-cream cones carefully marked down which once got BRIXMIS into hot water, with the Russians convinced the little drawing indicated nuclear detonation sites.
"They accused us of either plotting nuclear detonations of ours on them, or where we thought their nuclear storage sites were," Dave Butler explained.
"Because of the little conical shape of the cone and the little fluffy bit over the top, they thought these were little mini nuclear explosions," he added recalling the incident when the maps were taken out of one of the BRIXMIS vehicles by Soviet forces.
"Chief of Mission found [the incident] extremely amusing, and so did we."
BRIXMIS was based in a grand-looking manor house in Potsdam, just east of Berlin.
The East German staff were all on the Stasi payroll and the mission team found out later that the Stasi had also positioned a long-range microphone on the far side of the lake to try and pick up their conversations in the mission house grounds.
Teams would set off from here often targeting Soviet rubbish dumps at night or tank ranges and other exercise areas after Soviet troops had finished their manoeuvres to see what information they could glean from abandoned ammunition and equipment.
A lot of the taskings and clandestine intelligence gathering read like the pages of a "boy's own adventure" tale: brushes with Soviet troops and daring intelligence-gathering inside enemy territory.
It is clear all involved in BRIXMIS, and the American and French sister missions, loved the job, but this was not play-acting.
However, the risks and dangers were very real.
In 1984, French soldier Philippe Mariotti was killed when his vehicle was driven off the road by the Stasi.
A year later, in 1985, US Major Nick Nicholson was shot dead by a Soviet sentry.
Both incidents caused serious ructions and brought home the seriousness of the role.
BRIXMIS tours were out on the ground for days at a time.
They say they spent more time under canvas than any other unit in the British Army.
Before they bedded down for the night, they would conduct anti-surveillance, or "de-narking" as it was called.
The teams would sometimes drive hundreds of kilometres to shake off these tails.
They would sleep fully clothed, ready to go if they were disturbed.
Check out our special long read on BRIXMIS here and watch the Real Cold War Spies: BRIXMIS series on Youtube.