Details of the bizarre assortment of shopping-basket bombs made ready for Hitler’s planned invasion of Britain have emerged in the latest release of MI5 files.

However, the Nazis’ home-made explosives appeared to be about as effective as some of their propaganda. A mock-up Evening Standard front page is identified as the “Late Blighters Final”. The fake London paper, dated February 17, 1940, claimed that the RAF had been massacred and that Parliament had held a secret session to deal with the crisis. An advertisement on the front advised: “Take French laxative — it will keep you on the run.”

Christopher Andrew, a professor of modern and contemporary history at Cambridge University and the official historian for MI5, said yesterday that some of the propaganda pamphlets “looked more like Monty Python”.

However, judging by the extensive use of household items as covers for explosive devices, the German secret service took the sabotage and propaganda business seriously.

According to MI5’s files, the would-be German saboteurs had developed timer bombs to be concealed beneath false bottoms in workmen’s mess tins, complete with sausage, mash and peas. Bombs were also designed for shaving soap, torch batteries, blocks of wood, coal, tins of fruit salad, leather belts, tins of frozen eggs and stuffed dogs. Hitler’s chocolate bombs were given special prominence in the MI5 files, with detailed drawings of how they should work.

Designed as grenades, each “bomb” was made of steel with a thin covering of real chocolate. “When the piece of chocolate at the end is broken off, the canvas is pulled, and after a delay of seven seconds the bomb explodes,” the MI5 file explained.

Professor Andrew said that some versions of the German boobytraps revealed in the newly declassified files, entitled “German camouflage for sabotage equipment”, smacked more of Charlie and the Chocolate Factory than anything else.

“I believe German espionage and sabotage of the UK actually achieved 100 per cent incompetence in the Second World War,” he added.

Leaflets prepared for British eyes included pictures of healthy German babies contrasted with photographs of malnourished British children at death’s door. “Life is good for children in the Third Reich. Jolly, happy children live in Greater Germany,” one pamphlet boasted.

There were also references to Britain’s “economy recipes” to keep the people fed, including providing frogs for breakfast and shooting the deer in Richmond Park to be turned into sausages or pies. The MI5 files had one leaflet purporting to be from Hitler, which said: “You lice, vermin, spawn of prostitutes, how I hate you, Schweinehunde.”

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