To understand the origins of Chinese swimming's rise, we must take a Tardis back to the mid-1980s, our landing place Kreischa, in Saxony, the home of the East Germany anti-doping laboratory accredited by the International Olympic Committee.

If you expect the control centre of an official State Secret to be housed in an impressive, heavily guarded headquarters, think again.

We're talking about something not much bigger than a double garage, with a small entrance hall in between. It's built of prefab mortar and wood and sits, in renovated state these days, in the grand formal gardens and amid the fountains of a vast, stately clinic and rehabilitation centre.

The history of the place dates back to 1839 when a wealthy family founded a bathing and hydrotherapy facility on the site. In 1899 it became a centre specialising in conditions of the nervous system.

You'd have needed some nerve to have been an architect of what happened there more than half a century on, past two World wars and the division of Germany into East and West. The Berlin Wall would fall in 1989 shortly before the vast Bavaria Klinik would be built in Kreischa, but both back then, before and ever since, the inconspicuous single storey brick building in the grounds remains home to an IOC-accredited anti-doping laboratory.

In GDR days it was the keeper of secrets, dark arts and the alchemy required to turn a nation of around 16-17 million into a world-leading powerhouse in sport capable of toppling the Soviet Union and the USA in the sport of swimming.

On the day our Tardis lands there, memory of the future intact, we alight on an unexpected scene. There, at the door of the Kreischa laboratory to greet us is deputy director Dr. Dietrich Behrendt. Either side of him are "curious visitors", as the photo caption on the snap taken that day will say.

They're from China, they are "colleagues" from the world of medicine and sports science and they've made the trip a year after the first East German swim coaches headed to China to fast-forward the evolution of Olympic sport in the giant communist state.

A couple of years later, in 1988, Dr. Behrendt will travel to West Berlin on a business trip. He will choose the moment to escape to the West, returning home only after the fall of the Berlin Wall. The following words were among his contributions to truth:

"This laboratory was not founded with the goal of combating doping, but rather of enabling doping."

Twenty years or so after Dr. Behrendt received his visitors from China, I'm sitting in a café on the shores of a rowing lake in Potsdam, once a leading training centre for East German athletes, listening to the confessions of one of the GDR's leading sports scientists but it would be four years before a large boxed parcel would arrive stacked with a clearer view of the strength of connection between GDR, its doping administrators, and China.