Lance Corporal, later Captain, M K Townsend was awarded the Distinguished Conduct Medal in January 1975, as the result of his actions during an ambush in Western Dhofar.
He was leading a four man SAS liaison patrol attached to a company of the Sultan's Armed Forces, when they were attacked by 60 to 70 men with machine guns, rocket launchers and mortars from close range.
A number died immediately, and most of the rest of the men were overwhelmed by the shock and sheer weight of fire.
Townsend and two others ran forward and took machine guns from the company soldiers and returned fire, which was almost the only counter-attack at that point.
He then left the two others to return to the company's mortar, and co-ordinated it's move into position for it to commence firing.
Noticing that men at the front were still reluctant to shoot, he led by example, standing openly on a rock and shooting back while bullets landed all around him.
When ordered to stand down from this extremely dangerous position, Townsend co-ordinated the artillery fire.
His conduct was described variously as "magnificent", "fearless heroism" and "Courage in the very highest traditions of the service".
The Distinguished Conduct Medal is second only to the Victoria Cross - seen as a 'near miss' from being awarded a VC - and equivalent to the Conspicuous Gallantry Medal.
Townsend's DCM, alongside his General Service medal with two clasps for Northern Ireland as well as Dhofar, South Atlantic 1982 Medal with rosette, UN Medal for Cyprus and his Accumulated Campaign Service Medal are estimated at £40,000-60,000.
The lot also includes Townsend's record and several letters, most from senior army figures congratulating him, and one from Princess Diana thanking him for arranging her security in Angola.
Townsend's medals were stolen in 1988, and the lot includes the replacements he was given before the originals were returned.
The collection is to be sold at Spink's London auction on November 19.
