PREVIOUSLY secret files reveal spy chiefs told Suffolk police to keep an eye on Hitler Youth teenagers cycling through Britain.

Before the outbreak of the Second World War, parties of German boys criss-crossed the UK on bicycle, receiving warm welcomes almost everywhere they went.

But newly released MI5 files from the National Archives, show the agency was so concerned about the danger posed by the youngsters that it ordered police to report whenever they arrived in the country.

MI5 chief Colonel Sir Vernon Kell wrote to police in Suffolk, Norfolk, and Essex in July, 1937, stating a group of Hitler Youth cyclists would be arriving in Britain.

He said: “Should they come into your jurisdiction I should be very grateful for any information you can obtain regarding the places they visit.”

In August 1937, a report by a special branch officer of the Metropolitan Police with the subject ‘Hitler Youth’ detailed how a party of 22 Germans from a Bavarian branch of the movement arrived at Liverpool Street station in London after arriving at Harwich.

The officer said he followed the group, who were wearing the uniform of the Hitler Youth, on the Tube to Euston, where they were catching a train to Liverpool, but said there was “no untoward incident.”

The fear that German cyclists were carrying out covert spying operations in Britain appears to stem from a May 1937 article in the now-defunct Daily Herald newspaper.

Under the headline ‘NAZIS MUST BE SPYCLISTS’, it warned that the Nazi Cyclists Association had issued orders to its members who were spending holidays abroad.

A similar article in a magazine called The Cyclist a month later said touring German cyclists had been told: “Impress on your memory the roads and paths, villages and towns, outstanding church towers, and other landmarks so that you will not forget them.

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

MI5 was sceptical about the authenticity of these instructions, but collected dozens of reports of groups of uniformed Hitler Youth touring Britain.