A network of First World War training trenches found on a Norfolk campsite has been given special listed status only granted to sites of national importance.
The earthworks were constructed on land near the village of Stanhoe, in the north west of the county, to help troops prepare for battlefield conditions.
Their remains - which were discovered around ten years ago - have been designated as a 'scheduled monument' by Historic England.
The trenches were dug by the Lovat Scouts, a Highland yeomanry unit made up of Scottish estate workers, which was stationed in Norfolk ahead of deployment on the front line.
They were constructed in the late spring and summer of 1915 and comprise a set of front-line trenches and communication trenches to the rear.
Training trenches were dug all across England during the First World War to prepare soldiers for combat, but most have since been lost.
The Stanhoe network - which is now part of the Dreamy Hollow campsite - has been partly in-filled over the years and heritage experts believe it has "archaeological potential", with artefacts possibly buried there.
The site has around 2.5 acres of un-excavated ground, containing approximately two-thirds of the network.
In the inter-war period, the trenches were partly returned to agriculture and the 'enemy' trenches have been lost under ploughed land in an open field.
In 2012, the site was taken over by Nigel Day, owner of the Dreamy Hollow campsite.
He initially assumed the earthworks were drainage ditches, but thought something was "odd" about them, so contacted Norfolk County Council's archaeology department.
Experts studied aerial photographs taken by the RAF in 1946 which revealed the network.
Some of the trenches have been partially excavated to reveal their form.
The network is of particular interest to historians because of its links to the Lovat Scouts, who had a lasting legacy on the British army and the development of special forces warfare.
Historic England described the trenches as "eloquently" characterising the period of their creation.
A report said: "Surviving archaeological features and artefacts will enhance our understanding of the context and development of First World War trench construction and training conditions."
The Lovat Scouts
Initially formed in 1900 as two companies of Scottish Yeomanry by Simon Fraser, 14th Lord Lovat, they served in the Second Boer War.
The unit became known for its skills in marksmanship and fieldcraft, having been drawn from farmers and fishermen of the Highlands and islands of Scotland.
They also formed the first sniper unit of the British army and introduced 'ghillie suit' camouflage clothing, designed to resemble background foliage.
In April 1915, following a Zeppelin raid on King's Lynn, the Lovat Scouts were despatched to Hunstanton and the surrounding area.
The soldiers introduced their culture to the nearby towns and villages.
They wore traditional Highland outfits and performed concerts with bagpipes, leaving a lasting impression on locals.
The Lovat Scouts left Norfolk in September 1915. From there they joined the Gallipoli campaign and later served in Egypt, Greece and Italy.
The 15th Lord Lovat, himself later an officer in the Scouts, became a key figure in the development of the Commandos and special forces warfare, in the Second World War.
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