AT first glance it does not look much - three faint streaks on a grainy map of the North-East.

But to a team of researchers delving into one of the murkiest episodes of the Second World War, it could be historical dynamite - the most damning evidence yet that Britain's Royal Family welcomed Hitler's henchman Rudolph Hess with open arms.

The dusty charts housed on the shelves of the archives at Durham County Hall provide, they claim, startling evidence that Durham's Royal Observer Corps stood by and watched as the top level Nazi piloted his own Messerschmitt along our rugged coastline.

The research will be revealed in a TV documentary to be shown next month, put together by producer Richard Taylor, and based on the controversial findings of a new book, Double Standards: The Rudolph Hess Cover-Up.

The show will make the extraordinary claim that Hess's fate was intrinsically linked to that of at least one very senior Royal.

Authors Lynn Picknett, Clive Prince and Stephen Prior believe the Duke of Hamilton and the King's brother, Prince George, the Duke of Kent, were expecting the Deputy Fuhrer and were hoping to broker a peace deal.

They claim the map, recovered from the vast vaults of County Hall, Durham, shows Hess's twin-engined fighter-bomber hugging the North-East coastline, with his two-fighter escort about to turn back to the Fatherland - proof that our top brass knew he was coming and let him continue his date with destiny.

Officially, his was on a lone, crazed crusade to reach a peace settlement when he crash-landed 12 miles from Hamilton's estate, at Dungavel.

He was arrested, tried for war crimes at Nuremberg and sentenced to life imprisonment at Spandau prison, Berlin, where he died in 1987.

Either that, says the new theory, or he was the mystery man who died alongside the Duke of Kent in 1942 in a plane crash while on a mission to negotiate a pact with Germany.

According to the theory, the man who spent 40 years in Spandau was a double agent planted by British intelligence.

Producer Richard Taylor said: "What we are saying is that there were effectively two Rudolph Hesses - one who died in 1942 and one who died in 1987.

"If this is correct, and we believe it is, it has the potential to rewrite history. The map establishes that he was not flying alone and was seen at the early stages of his approach.

"No Spitfires were scrambled to intercept him and he was allowed to fly, sometimes at a height of only 50ft, all the way to Glasgow. He was so low in fact that one witness describes seeing his plane fly through the smoke from a steam engine funnel."

Hess took five hours to fly the 900 miles from Berlin before his fateful meeting with a Scottish farmer, when he bailed out after twice missing the duke's landing strip. When he was handed over to British authorities, the Royals covered their tracks and denied all knowledge of the peace mission.

Durham County Council was sceptical when informed of the historical dynamite lying undiscovered in their archives.

"You should see what else we've got down in that vault," said a wry spokesman.