Did Hitler's young disciples recce Britain by bike?

Pre-war cycling tours of Britain by groups of Hitler Youth riders were enough to alert the finely tuned antennae of MI5, declassified documents have shown.

Files released by the National Archive show that in the summer of 1937, the security services became interested in the sight of Aryan youths inspecting the highways and byways of Great Britain by bike.

Alerted by a (possibly scurrilous) article in the long-gone Daily Herald entitled 'Nazis must be spyclists', MI5 decided to keep a watch on the Germans.

The article quoted instructions apparently circulated in a cycling journal compiled by the German government, which asked sportsmen to memorise their surroundings while abroad.

“Make a note of the names of places, rivers, seas and mountains,” it read. “Perhaps you may be able to utilise these sometime for the benefit of the Fatherland.”

While the exact source of these comments was never found, they were enough for Vernon Kell, head of MI5, to order the monitoring of the Hitler Youth. His agency alerted police forces to look out for youths wearing “dark navy blue uniforms, consisting of shorts and loose open-neck tunics”.

Obedient Metropolitan Police officers followed them in London, while police in Denbighshire observed that the Hitler Youth swapped hats with local scout groups in Colwyn Bay.

The cycling itineraries of the Hitler Youth were collected and may seem suspicious. Highlights of their tours included steelworks in Sheffield and gasworks in Glasgow. The file also includes information on the suspects’ visit to Spalding Rotary club, where they enjoyed a “sausage and mashed potato supper”.