On graduating and beginning a professional career, Lambert won gold in a championship record time at the 2003 European Athletics U23 Championships. He then became an Olympian, securing selection to TeamGB for the 2004 Olympic Games in Athens, but due to injury he surrendered his place on the 4x100m relay team that went on to win the gold medal. He claimed a silver medal at the 2005 European Athletics Indoor Championships then in an injury-plagued career he was also selected for but had to withdraw from the 2002 European Athletics Championships, 2005 IAAF World Championships in Athletics and 2006 Commonwealth Games.