The estimate was £40,000-£60,000.
Lance Corporal Justin R. Thomas of 40 Commando division of the Royal Marines was awarded the first CGC of the Iraq War for his extreme bravery in a commando attack mounted against an enemy battalion in the Abu-al-Khasib area near Basra in the early days of the campaign on March 30, 2003.
Pinned down by hostile fire and with many of his comrades in exposed positions, he ran from a place of comparative safety and climbed onto an open-top vehicle where he manned the mounted machine gun.
He singlehandedly returned a heavy weight of sustained fire for a continuous period of nearly 15 minutes while small arms and rocket-propelled grenades landed all around him.
"I'm not exaggerating, there were hundreds of rounds coming close to all of us on any given day.," he said. "You wouldn't be able to count the number of times you could have died."
A 17-page chapter detailing his exploits appears in the book In Foreign Fields by Dan Brown.
The Conspicuous Gallantry Cross was instituted as a result of the 1993 review of the British honours system and is second only to the Victoria Cross in seniority. It was awarded for the first time as a result of the Bosnian War in 1995 and to date 33 have been issued.
Lance Corporal Thomas's C.G.C. was the first of 13 awarded during the Iraq conflict and, as most remain with their recipients, it is believed to be the only example to have appeared on the market to date.
Justin Thomas, 30, has now left the Marines and works as a civil servant.
Dix Noonan Webb told ATG there were a number of bidders hoping to acquire the rare group, sold together with related ephemera including letters of congratulation, photographs, military issue maps, record book, identity card and four pieces of clothing bearing the Royal Marine Commando insignia.
Internet bids of this magnitude are unusual as buyers incur an additional three per cent buyer's premium to use the online service - bringing the total bill here to £108,240.
Previously the highest successful bid posted on the-saleroom.com was the £38,000 for a cello by William Forster, London c.1780, sold by musical instrument specialists Brompton's in November 2008.
The top lot of the September 17-18 sale of Orders, Decorations, Medals and Militaria was the C.B.E. and Polar Medal awarded to Commander John Robert Francis "Frank" Wild (1873-1939), the only man to explore Antarctica five times during the so-called Heroic Age.
Wild was among those to volunteer for the National Antarctic Expedition under Scott in 1901 and famously was second-in-command of the British Imperial Trans-Antarctic Expedition of 1914-17. Between April 24 and August 30, 1916 he performed the onerous task of holding a party of men together on the desolate Elephant Island while Shackleton made his famous rescue voyage to South Georgia.
His four-clasp Polar Medal sold here at £110,000 is unique.
By Roland Arkell