The robbery on CCTV and a bystander's video camera

New Scotland Yard and Agencies

Two thieves who carried out Britain's biggest ever jewellery heist may have hidden their faces with elaborate rubber masks, it was reported yesterday, as detectives arrested a man in east London and later recovered a loaded gun.

The pair were said to have hired a make-up artist to disguise themselves with liquid latex before their £40m raid from the exclusive Graffs in Mayfair, London.

The 29-year-old artist thought he was transforming them for a pop video and altered their hair colour and skin tone in a four-hour session that cost £450, according to the Sun.

Forensic experts seized items including hairbrushes, gowns and banknotes from a make-up studio in Covent Garden, central London, the paper said. A Metropolitan police spokesman declined to comment.

On Wednesday flying squad officers arrested a 50-year-old man outside a house in Ilford, east London. He has been released on bail pending further inquiries.

Officers have raided several properties in the capital and are following up new lines of inquiry after the release of CCTV footage showing two men entering the store in New Bond Street.

Detectives said last night they had recovered a loaded firearm connected to the crime. Scotland Yard also said that the cars used in the thieves' getaway had fake licence plates.

The two armed robbers – one white and one black, and both dressed in smart suits – made off with 43 items of jewellery in the heist last Thursday. They were filmed on CCTV entering the shop. Once inside they pulled out handguns before snatching expensive items from a cabinet.

Dragging a female member of staff outside, they fired a warning shot before releasing her and making their escape initially in a blue BMW that an onlooker caught on mobile phone video.

It is thought they were helped by a series of getaway drivers. A second warning shot was fired as they changed vehicles nearby. A Met spokesman said: "Following the release of CCTV images of two men they want to speak to, officers are currently following up a number of inquiries."

Disguises have played a vital role in other heists. In 2006 the gang behind the largest robbery ever in Britain, a £53m-haul from the Securitas depot in Tonbridge, Kent, used professional prosthetics.