New research by the National Archives highlights the “use of the derogatory word”.

But campaigners have slammed the dig at the World War Two PM.

It is in a blog by archives author Mark Dunton on Churchill’s secret voyages to meet other Allied leaders.

In 1941 Sir Winston wrote to US President Franklin D Roosevelt: “We are just off.

It is twenty-seven years ago today that Huns began their last war. We must make a good job of it this time. Kindest regards.”

Mr Dunton goes on to warn his readers: “The use of the derogatory word ‘Huns’ to describe the Germans obviously needs to be viewed in the historical context.”

The National Archives, at Kew, South West London, is “guardian of some of the nation’s most iconic documents”.

But Chris McGovern, of the Campaign for Real Education, insisted: “It is demeaning, shameful and barmy.

“It doesn’t help anyone if common historical terms require trigger warnings. If people using the archives have to be protected from such terms, where does it end? Huns was a term used by heroes to describe what they saw as Nazi atrocities.

“The National Archives are the custodians of our national history, they shouldn’t be sanitising the past.”

The Hun were originally a 5th Century nomadic Asiatic tribe.

Germany’s Kaiser Wilhelm II used the term for his troops during the 1899 Boxer Rebellion in China.

The term was widely used by the Allies during World War One.

A National Archives spokesman said: “There is no trigger warning on the blog. The author included a line within the text to explain a derogatory term no longer commonly used.”