IT was one of the most daring missions of the Second World War - and the stakes had never been higher.

A group of saboteurs were given the task of destroying a Norwegian factory and thus preventing Nazi Germany from building an atomic bomb.

Part of their specialist training took place at Beaulieu in the New Forest.

During the war a group of secluded country homes on the Beaulieu Estate were used as a training school by the Special Operations Executive (SOE), which masterminded the Norwegian raid.

Yesterday the Princess Royal met one of the most famous saboteurs when she opened an exhibition about the top-secret operation.

Joachim Ronneberg and 11 other saboteurs were sent to destroy the Norsk Hydro plant in the Telemark region of Norway in February 1943.

The heavily guarded factory produced heavy water, one of the materials used to control atomic fission.

Mr Ronneberg and fellow members of Operation Gunnerside broke into the complex and placed explosives in the basement, destroying about a ton of heavy water and disrupting production for several months.

The saboteurs were anxious to prevent any reprisals being taken against local Norwe-gians.

They left English tools behind in a successful attempt to convince the Nazis that the heroic raid had been carried out by UK commandos.

Their exploits were later immortalised in the film The Heroes of Telemark, starring Kirk Douglas and Richard Harris.

Mr Ronneberg returned to Beaulieu yesterday to present Lord Montagu with a bottle of the colourless liquid that almost changed the course of the war. The 85-year-old was trained at a house called The Drokes, one of 11 homes in the parish that were requisitioned by the organisation.

He said: "I spent a fortnight in the area in 1941 and was taught all sorts of things, including silent killing, how to be observant and how to behave if you were caught."

About 3,000 spies and saboteurs passed through Beaulieu between 1941 and 1943.

The exhibition is housed in a single-storey building next to Palace House, ancestral home of Lord Montagu of Beaulieu.

Lord Montagu was evacuated to Canada in 1940 but returned in 1942 - only to find parts of the estate were out of bounds.

He said: "It was always my dream to mount an exhibition worthy of those brave men and women, some of whom gave their lives."

WEAPONS OF THE SOE:

EXPLODING rats were among the 007-style devices used by SOE agents.

Dead rodents packed with plastic explosives were placed near fires and furnaces at factories making products for German forces.

Guards found the rats and threw them in the flames, resulting in an explosion.

However, the tactic is thought to have been used only a few times before the Germans realised what was going on.

Exploding horse dung was another weapon at SOE's disposal.

Manure on the road concealed a tyre-burster - a small device containing plastic explosive that was detonated by the weight of a passing vehicle.

For more pictures see the Forest & Waterside edition of today's Daily Echo.