Born in 1973 and raised in Suffolk where he was a keen member of the Essex and Suffolk Pony Club and represented GB as an individual at the Pony European Eventing Championships. After leaving school Spencer worked as a working pupil for Ruth McMullen, Lucinda Green and Mark Todd. The decision to switch to dressage came when he realised he wasn't brave enough, to stay in eventing.
Spencer won his first Dressage National title in 1999. In 2006 he made his first international debut. To date Spencer has won 13 National titles. and in 2016 he achieved a Silver team medal as part of the British Dressage Team selected for the Olympic Games in Rio De Janeiro.