As of July 2022, Richardson was ranked joint third in the all-time Great Britain lists for 400 metres[2] Richardson competed for Great Britain in the 1996 Summer Olympics held in Atlanta, United States in the 4 x 400 metre relay where he won the silver medal with his team mates Iwan Thomas, Jamie Baulch and Roger Black.

At the 1997 World Championships in Athens, Richardson ran the anchor leg for Great Britain in the 4 × 400 m relay, winning the silver medal.

[8] Unlike fellow competitors Linford Christie, Gary Cadogan and Doug Walker, Richardson accepted the ban and chose not to pursue his case to arbitration.

[9] UK Athletics also cleared Richardson (as they did with Christie, Cadogan and Walker) as they believed there was enough reasonable doubt over the intention to take a banned substance.

[10] He never managed to win a solo gold medal at a major championship and retired from the sport after failing to recover from an Achilles tendon injury towards the end of 2003.