Adolf Hitler tried to infiltrate the boy scout movement in Lincolnshire, according to newly released secret documents from the 1930s.

Declassified files from the National Archive reveal that the county played host to 22 apparently innocent young Germans who said they were on a cycling tour of Britain in 1937 and 1938.

But concerns about this group of 'students' arose as MI5 discovered Lord Baden-Powell, the founder of the Scout movement, was invited to meet Adolf Hitler after holding friendly talks about forming closer ties with the Hitler Youth.

The group of black-clad so-called 'spyclists' was treated to a "sausage and mashed potato supper" at a gathering with a "grand party spirit" organised by the Rotary club in Spalding, in the south of the county, in August 1937.

Lincolnshire's chief constable wrote to Special Branch alerting them that the visitors were in fact members of the South Bavarian troop of the Hitler Youth, it has emerged.

Roy Donner, 56, a member of Lincoln Scout Fellowship, said he was not surprised by the revelations.

"I think both sides were up to dirty tricks," said Mr Donner, of Claremont Street, off Monks Road, Lincoln.

"By 1937 the Scouting movement in Britain was 30 years old and was becoming a huge youth movement both here and across the world.

"What I feel though is that the ideals of our Scouting movement are poles apart from Nazism."

In May 1937 the Daily Herald newspaper, under the headline "NAZIS MUST BE SPYCLISTS", warned that the Nazi Cyclists' Association had just 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 to memorise the geography of Britain "for the benefit of the Fatherland".