Having retired from a 17-year rugby career at Harlequins in the summer of 2020, Mark joined the RPA as Head of Rugby Policy. Mark represented England at age-group level, and Saxons. He won one Premiership title back in 2012, the LV= Cup in 2013 and one European title in 2011. Lambert went onto make over 250 appearances for Harlequins. Mark served as Chair of the RPA Players Board between 2017-2020.