A Chronograff mens 45mm watch with leather strap and pink gold buckle, which was stolen by two smartly-dressed armed robbers entering Graff Jewellers in London's West End

A pair of white round diamond double hoop earrings with a white pearshape and round diamond top, which was stolen by two smartly-dressed armed robbers entering Graff Jewellers in London's West End

An image from CCTV footage of two smartly-dressed armed robbers entering Graff Jewellers in London's West End

A raid on a Mayfair jeweller is believed to be the biggest gems heist in British history, it emerged today.

Two smartly-dressed armed robbers stole jewellery worth almost £40 million from Graff Jewellers in London's West End last Thursday.

Scotland Yard issued CCTV images of the duo today as they conned their way past a security guard at the prestigious New Bond Street shop.

Once inside they pulled out two handguns and threatened staff before snatching expensive rings, bracelets, necklaces and watches.

After arriving in a black taxi, they fired two warning shots into the ground as they escaped in a series of vehicles across Soho.

Detective Chief Inspector Pam Mace, of the Flying Squad, said the pair are "extremely dangerous".

She said: "This was a well planned robbery with a number of vehicles used to help the robbers escape.

"These men are extremely dangerous and fired at least two shots in busy London streets as they made their getaway. Someone knows who these men are.

"They would undoubtedly have spoken about it beforehand or boasted about it afterwards.

"I would urge anyone who recognises them, knows the whereabouts of the jewellery or has any other information to contact us."

The heist dwarfs what is thought to be Britain's previous biggest jewellery robbery, a £23 million raid at the same store in 2003.

Police also released images of some of the 43 items of jewellery stolen in the raid, including a pair of white round diamond double hoop earrings.

Other items to be taken included a yellow diamond flower necklace, platinum white Marquise diamond ring and a Chronograph men's 45mm watch.

The robbery took place at 4.20pm last Thursday after the men got out of a black taxi in New Bond Street.

After grabbing the jewellery, the men took a woman staff member outside with them and fired a shot into the ground as they got into a blue BMW.

The car was driven into Old Bond Street, and on to Stafford Street before smashing into a taxi in Dover Street.

A second shot was fired into the ground as they abandoned the car and switched to a silver Mercedes, which continued towards Berkeley Square.

The car then drove into Farm Street, where police suspect the men got into a black vehicle, possibly a Ford Galaxy or VW Sharan.

Police said both men were well-dressed, aged in their 30s and spoke with London accents.

The first was about 6ft tall, of slim build, with dark hair and a well-combed side parting. He was wearing a grey suit, white shirt and tie.

The second man is black, about 6ft tall, more well-built than the first suspect, with very short Afro hair. He was also wearing a grey suit, white shirt and tie.

The same store lost jewellery worth £23 million in a robbery in 2003 when two Serbians armed with a wig, a revolver and a scooter held up staff.

The robbery was carried out by a gang of gem thieves dubbed the Pink Panther gang. One Serbian criminal was wrestled to the ground as he fled and was later jailed.

In 2007, jewellery worth up to £10 million was stolen from a branch of Graffs Diamonds in London's Sloane Street by two men posing as customers.

The men arrived in a chauffeur-driven Bentley Continental Flying Spur before threatening staff at gunpoint.

Anyone with information should contact Barnes Flying Squad on 0208 247 4804 or Crimestoppers on 0800 555 111.

Belfast Telegraph