Harlee Dean joined Blues from Brentford for an undisclosed fee on 30 August 2017 on a three-year contract, with a year's option.
The central defender had been with the Bees since November 2011, where he clocked up an impressive 249 appearances and scored ten goals.
Born in Basingstoke, Dean ,who stands 6ft 3in tall, began his professional career with Dagenham & Redbridge, before undertaking loan spells with several non-league outfits.
In 2010, he was snapped up by then League One club Southampton, but left St Mary's two years later, without having made a first team appearance for the Saints.
After a successful loan spell at Brentford, he penned a permanent deal with the Bees in May 2012.
During his time at Griffin Park, he helped Brentford to a League One runners-up spot at the end of the 2013–14 campaign.
His efforts for the team were also recognised with him twice winning the club's Player of the Year accolade.