The Soviet Union secretly mapped Yorkshire during the Cold War. This map shows Halifax.

Like all good detective stories it began with a chance encounter. It was early 2000 when map enthusiast John Davies was working in Eastern Europe and as he often did during his downtime he sought out a local bookshop.

“I was flicking through some old maps they had and came across one of London,” he says. “I knew it was special, but it was only when I got talking to the owner that I realised how special.”

That map turned out to be part of a once secret cachet compiled by the Soviet Union during the Cold War. Plotted with detailed accuracy, they showed not just the location of military and industrial sites, but pinpointed individual streets and covered towns and cities across Yorkshire.

One of the secret Soviet maps showing Leeds city centre. Read more at: http://www.yorkshirepost.co.uk/news/analysis/how-the-soviet-union-secretly-mapped-yorkshire-during-the-cold-war-1-8847409

“Knowledge is power,” says Bradford-born Davies, who is co-author of the new book The Red Atlas. “These weren’t maps for the event of a nuclear holocaust. Rather it seems to me these maps were made on the assumption that at some point communism would reign victorious. If you are going to march into a foreign town and start running things, you need a good map.”

It is not known how many cartographers were involved in the project, but for years the maps they created were stored in 25 or so depots across the Soviet Union.

However, with the fall of the Berlin Wall in 1989, the break-up of the old regime began at speed and the depots, including the one in Latvia, were abandoned.

“The locals living nearby knew nothing about it,” says Davies. “However, by the early 1990s the maps began to find their way into public hands and were sold off and scattered across Europe.”

One of the secret Soviet maps showing Leeds city centre. Read more at: http://www.yorkshirepost.co.uk/news/analysis/how-the-soviet-union-secretly-mapped-yorkshire-during-the-cold-war-1-8847409

With his interest piqued, Davies embarked on a mission to not only track down as many of the Soviet maps as he could, but also uncover the story of how they were made.

“A number of them were compiled, at least in part, by using old Ordnance Survey maps and often things get lost in translation. There is one map which shows the Pennine villages above Huddersfield and pinpoints one of the old Mechanics Institutes which were set up in the Victorian era to give working men access to education.

“That didn’t mean anything to Soviets, and so they translated it as Institute of Technology and no doubt imagined some gleaming state of the art college.”

However, with the Soviets distrustful of publicly available maps, believing they contained deliberate mistakes to mislead an enemy just as their own did, they didn’t just rely on existing information. Instead, they also relied on satellite imagery and spies and sympathisers on the ground.

“There are some details which really stop you in your tracks,” adds Davies. “They don’t just include factories, they also include what was made in them. That kind of information is quite eerie because it confirms what we always thought - the Russians were watching.

“In the end they often ended up with too much information. When they got word of a new road or housing estate they just put it on top of what was already there, so often you get one grid reference referred to in two or three different ways.”

However, despite the odd error - in one map of Teesside a gas pipe line has become a road under construction - the Soviet maps were far better than those produced by most other countries during the same period.

“When the US first invaded Afghanistan in 2001 they used these old Russian maps because no others were as comprehensive - they even had the times of the year when the mountain passes were clear for travel. They are a piece of a big geopolitical jigsaw puzzle, but more than that they are works of art.”