By Lucretia Munro David Beckham has commenced legal proceedings over a fitness brand deal with actor Mark Wahlberg after claiming it cost him £8.5million. The legendary footballer’s company, DB Ventures Ltd had joined forces with gym group F45 along with Mark and had agreed to be the firm’s global ambassador. David and Mark had forged a friendship after the sportsman and his wife Victoria moved to LA in 2007, and lived in the same Beverly Hills neighbourhood. But now, David is reportedly claiming that he was “duped” by the Hollywood star. According to The Sun, David is claiming that he was pro…