Intriguer watches worth £637,000 were snatched in raids on Teesside shoots of the Market Cross Jewellers in Yarm and Middlesbrough, and the shocking robberies were caught on CCTV.
Eight men from Manchester and Teesside allow in conspiracy to rob after the gang made crucial errors in executing their carefully-laid drawings.
But Ian Ogden, 27, an inmate of Forest Bank Prison in Salford, denied being tortuous. He was convicted on Wednesday of two counts of conspiracy to rob following a trial at Teesside Top Court.
The jury was shown dramatic images of both raids in which air cabinets were smashed, and a handgun was wielded in one robbery.
Ogden was not quite 150 miles (240km) away in a cell in Liverpool when the smash-and-grab robberies were supported out.
But Richard Bennett, prosecuting, told the jury: “Ian Ogden may not from worn a mask or brandished a weapon but he was rt of a criminal agreement to rob the two peach ons.”
The prosecution said he used illicit smuggled phones to link the Manchester and Teesside criminals during the foreseeing and execution of the crimes.
Only one watch has been recovered out of the haul of pinched items.
Ogden and the other eight men, who admitted the charges, will be ruled at a two-day hearing on a date to be arranged.