Sassoon won the Military Cross for helping wounded comrades

Siegfried Sassoon's Miltary Cross, which was found on the Scottish island of Mull 90 years after it went missing, was due to be auctioned.

But a private agreement has ensured the medal will not leave Britain or become part of a private collection.

The World War I medal is to go on show at the Royal Welch Fusiliers' museum at Caernarfon Castle in Gwynedd.

Military Cross

It will be part of a new display of artefacts from artists and poets who served with the Royal Welch Fusiliers.

The private deal has been struck to sell the medal jointly to the museum trust and the poet's grand-daughter, Kendall Sassoon, and her family.

It will be displayed along with memorabilia of artists including Robert Graves and David Jones.

Major General Jon Riley, chairman of the Royal Welch Fusiliers Museum Trust, said: "Siegfried Sassoon and his contemporaries are a cherished part of our regimental family, and we take enormous pride in keeping their memory fresh."

The family of Siegfried Sassoon believed he had hurled his Military Cross into the River Mersey in protest over the war.

But the medal was found 90 years later at Benbuie Lodge on Mull.

Siegfried Sassoon was treated for shell-shock in Edinburgh

The item, along with Sassoon's identification tag, had been expected to raise up to �25,000 at auction.

His Webley revolver, which was also found in the attic, has been given to the Imperial War Museum.

Sassoon achieved renown for his vehement criticism of the war and was acclaimed as a writer of satirical anti-war verse.

His medal was discovered by Robert Pulvertaft, whose stepfather George was Sassoon's son.

Mr Pulvertaft was clearing out the attic when he came across the award.

Sassoon, who was known as "Mad Jack" for his acts of bravery, won the Military Cross for bringing in wounded and dying comrades lying close to German lines in 1916.

Famous soldier

He returned to Britain in April 1917 after being wounded and became increasingly disillusioned with the war. He later refused to return to duty.

Rather than court martial a national hero, the army sent Sassoon to Craiglockhart Hospital near Edinburgh to be treated for shell-shock.

The same year he was thought to have hurled the medal into the Mersey in a "paroxysm of exasperation".

But it was only its ribbon that he had sent floating away on the river.