Maughan denied the charges but was found guilty by a jury
Two men have been jailed after stealing nearly £4m worth of jewellery in a raid on an Essex airport.
About 2,000 Cartier items were stolen from Southend Airport in May 2001.
A jury at Basildon Crown Court found Joseph Xenofondos, 35, from Loughton, guilty of conspiracy to steal. He was jailed for five years.
Gary Maughan, 43, from north London, was found guilty of conspiracy to steal and handling stolen goods. He was sentenced to six years imprisonment.
Marios Xenofondos, the 39-year-old brother of Joseph, from Stoke Newington in Greater London, had previously been cleared of any involvement in the raid.
Tom Baisden, 28, of Thundersley, Essex, who trained as a chef with Jamie Oliver for a television programme, previously admitted one count of theft, one count of conspiracy to steal and one count of perverting the course of justice.
Xenofondos has been sentenced to five years imprisonment
The court was told he was the "inside man" during the robbery. He is awaiting sentence.
During the trial prosecutor Chris Paxton said the gang escaped with watches, keyrings, pins, sunglasses and belts.
Baisden, who was part of the Fifteen restaurant project in 2007, confessed to the crime last year.
He said he had carried out a test raid with the Xenofondos brothers and nurse Maughan.
Mr Paxton told the court that Maughan was Baisden's cousin and the Xenofondos brothers were associates of Maughan.
He told the jury Baisden had been working in a warehouse at Southend airport which handled freight - including shipments of Cartier goods.
Moved to Barbados
Goods had been loaded onto a lorry when Baisden was alone at the warehouse.
Baisden was beaten and tied up to look like a victim, the court was told.
Tom Baisden appeared on TV show Jamie's Chef with the celebrity
The court heard the four men had "enjoyed the fruits of their crime" for several years and Maughan had moved to Barbados.
Then, in May 2008, Baisden had done an "extraordinary thing" by telephoning Essex police and telling them who had committed the crime, Mr Paxton said.
Baisden finished runner-up on the Channel 4 show and planned to set up his own business with a fellow contestant.