The incredibly rare Conspicuous Gallantry Cross (CGC) won by a soldier who advanced at a Taliban force firing his machine gun from the hip and killing two of them is to be sold.

Colour Sergeant Alwyn Stevens from St Helena in the South Atlantic was a sniper in the Royal Irish Regiment.

In 2008 he was leading an Operational Mentor Liaison Team of six in Helmand Province.

When a local informed him that a Taliban force was planning an ambush he pushed forward to secure a compound which he might be able to defend.

Before he arrived there a force of eight Taliban opened fire, but the then-Corporal Stevens charged the enemy firing from the hip.

He killed two of the insurgents and wounded a third as the others ran into a field of corn to hide.

But the action was far from over. The enemy kept up their fire and launched rocket propelled grenades.

Stevens rallied his men and organised them to try and win the firefight; then more Taliban fighters turned up.

He then decided to call in an airstrike on the Taliban’s position even though he was just 120m (392 feet) away from them.

He and his team put down controlled fire to prevent the Taliban escaping before the bombs were delivered.

Following this, Stevens led an assault on another enemy position, attacking from the front with grenades and personal weapons. The attack accounted for most of the enemy with the rest fleeing.

For three more hours the battle raged until Stevens and his men were out of ammunition.

He held his position for his men to withdraw and only when they were relatively safe did he join them.

The medal is to go under the hammer at a sale organised by Dorchester-headquartered Duke’s auctioneers at the Tank Museum in Dorset.

The CGC is just one below a Victoria Cross and very few are awarded, meaning their value is high. The estimate for Stevens’ medal group is £120,000-140,000.

Adam Chapman from Duke’s said: “This is an almost unbelievable action; really awe-inspiring bravery.

“Reading the citation shows the level of commitment he had to his men and his selfless leadership.

“Due to Ramadan there weren’t many Afghan soldiers available and Alwyn was leading a handful of men on patrol.

“What followed was remarkable – he advanced on eight approaching Taliban firing from the hip, when he unexpectedly encountered them in a compound and they engaged him with small arms fire.

“There followed a great deal more fighting that lasted for three hours, including calling in danger close airstrikes to accurately neutralise the enemy combatants.

“Only when their ammunition supplies were nearly exhausted, did Colour Sergeant Stevens organise a withdrawal, which he stayed behind to cover.

“There will be many collectors and institutions who would love to have this medal group.

“The CGC was only introduced in 1993 and it is rarer than the VC in terms of the number awarded.”

Colour Sergeant Stevens, a father of four now living in Inverness in Scotland is selling his medals to help secure his family’s financial stability.

Speaking of the action, he said matter-of-factly: “I came across them, shot them and called airstrikes on their positions.

“The training kicks in, you rehearse your drills in the UK, and you rehearse and rehearse.

“That is what keeps you alive, and then the adrenaline kicks in.

“You don't have much time to think, it is more of a reaction, but if I hadn't done what I did, I probably wouldn't be here today.”

Part of his citation read: “Stevens displayed extraordinary courage, selflessness and leadership. He personally engaged and killed several Taliban Fighters and set conditions for the defeat of a strong enemy force. His actions ensured the enemy never again appeared in such strength in the ATTAL area during Operation HERRICK 8'.”

Corporal Stevens was awarded the CGC, announced in the London Gazette, on 6th March 2009. It was presented by the Queen at Buckingham Palace. Remarkably three soldiers from the Royal Irish Regiment were awarded the CGC for that tour.

His full list of medals is: Operational Service Medals for Sierra Leone and Afghanistan, as well as the Operational Telic Medal (Iraq), the General Service Medal with Northern Ireland clasp, the Accumulated Service medal 2001, the Queens Diamond Jubilee Medal, the Long Service and Good Conduct Medal.

Corporal Stevens retired from the army in October this year.

Nik Wyness from The Tank Museum said: “This is just one of many fascinating items that will feature in the Duke’s medals and militaria auction taking place at The Tank Museum.

“The quiet heroism of our soldiers never fails to inspire and this medal group will certainly attract a great deal of interest.”

The sale is to be held on Saturday November 6.