What is believed to be the only surviving complete Assault Ration Pack in the world has been found in Dorchester.

Staff at the Keep Military Museum have discovered the Second World War ration pack - including tea, chocolate, meat and more - in the museum collection.

The Assault Ration Pack was issued to British and Commonwealth soldiers for the D-Day landings, and was designed to sustain the troops for an additional 2 hours while supply chains were established.

Originally found in 2006, the sealed ration pack was mistakenly identified as a 1950s item. But when it was re-examined recently for a military rations exhibition, the museum's director instantly recognised it as the extremely rare assault rations of the Second World War.

Remarkably, x-rays of the ration pack show all the original contents still inside - including the biscuits, boiled sweets and tea. The team at Keep Museum is grateful for its friends at Fishbourne Roman Palace for the expert assistance in x-raying the box.

The rations were packed in a waxed cardboard box, which was sealed to help keep the contents water and gas proofed. Their small size allowed them to be carried in a mess tin. They were a lightweight solution to providing a soldier with the 4,000 calories he needed in a day.

The pack contained:

• 10 biscuits
• Two oatmeal blocks
• Tea, sugar and milk blocks
• One meat block
• Two slabs of raisin chocolate
• One slab of plain chocolate
• Boiled sweets
• Two packets of chewing gum
• One packet of salt
• Meat extract tablets
• Four tablets of sugar
• Four pieces of latrine paper

June 6 marked 78 years since the D-Day landings and the allied invasion of Normandy, laying the foundations for the victory in Europe and ultimately the end of the Second World War.

Elliot Metcalfe, the museum's director, said: "D-Day is central to the story we tell here because our regiments - the 2nd Devons and the 1st Dorsets landed on Gold Beach near Arromanches at 7.30am that morning. In fact, the 1st Dorsets - with the 1st Hampshires beside them - were the first British infantry to land on D-Day.

"We're very proud of that - and we're thrilled to have found this ration pack which every soldier carried that day. It's strange to think that this seems to be the only one left in the world."