The 6'4" centre back would come in for Leon Cort, who City sold to Crystal Palace for £1.25million, leaving just Damien Delaney, Sam Collins and the injured Danny Coles as options for Phil Parkinson.
Turner was a trainee for Charlton Athletic, and they take a cut of the transfer fee due to the sell-on clause in his contract. He didn't make a first team appearance for the Addicks, and had a 7-game loan spell with Leyton Orient in 2003. He then joined Brentford on loan in 2004, before making the move permanent for a nominal fee in November of that year. In addition to the 16 loan appearances, he made a further 94 starts in all competitions, scoring 3 goals. He was at the heart of the Bees defence that kept 22 clean sheets last season en route to making the League One play-offs.
Meanwhile, City have revealed that Stuart Ayles has joined the club as Fitness Coordinator. He agreed terms on the 22nd June, just days after resigning at Colchester, and will start work next week.