Court clears two men of participation in the £40m jewellery theft.
Thomas Thomas, 46, has been found guilty by majority verdict, at Woolwich Crown Court, of conspiracy to rob Graff Diamonds.
His role was to block traffic in nearby roads with a truck to allow for the quick getaway of the robbers.
The robbery of the Mayfair jewellers took place in Mayfair last August. £40 million of jewellery was stolen and has yet to be recovered.
Thomas was the second man to be convicted over the incident. Aman Kassaye, 25, was convicted earlier this month for kidnapping, conspiracy to rob and carrying a gun.
Two other men, David Joseph, 23, and Courtney, Lawrence, 31, have been cleared of all charges.
Thomas was reportedly recognised by shop assistant Petra Ehnar, who was held at gunpoint during the raid.
Five other men are still awaiting verdicts. It is probable those who planned the raid remain at large.