Stoneman began his motorsport career in 2002 in karting, where he was active until 2006. He also made his first experience in Formula racing series in the winter the British Formula Renault BARC Formula Renault and in which he took each to three races. 2007 Stoneman won the runner-up title of the BARC Formula Renault. He then competed in the British Formula Renault Winter Series, finishing in sixth place overall. In 2008 he started again in the winter series of the British Formula Renault, and improved to third place overall. His main focus was on the 2008 and 2009 British Formula Renault. He was fourth in the championship in both years.
2010 Stoneman moved into Formula 2 After starting in his debut race with a second place finish the season well, he already won the second race weekend in Marrakech his first race. Initially he took second place overall, he took over in the second half of the season the championship lead and eventually won with a total of six wins the championship ahead of his compatriot Jolyon Palmer. He then took on the last race weekend of the 2010 season for Mofaz Racing part in the Formula Renault 3.5, finishing in 26th place overall. As a reward for the Formula 2 title Stoneman was allowed to participate in Formula 1 test driving for Williams in November.
2011 Stoneman planned for ISR Racing as team-mate Daniel Ricciardo in Formula Renault 3.5 to go to the start. Stoneman, however, had to cancel for health reasons before the start of the season in January of that year to participate, since he was diagnosed with testicular cancer. The end of November Stoneman returned after successful treatment of the race car back and took part in Formula Renault 3.5 test drives for ISR Racing. ISR Racing held for Stoneman over a longer period a Formula Renault 3.5 cockpit free, but for financial reasons it did not come to this commitment. Stoneman graduated in winter 2011/2012 also test drives in the Indy Lights. Also in this series failed for exposure to the budget. Then took Stoneman in Formula 2 participated in test drives.
Since Stoneman in 2012 found no permanent race seat in car racing, he took part in motor boat racing. He succeeded, British powerboat champion in the P1 SuperStock be. In auto racing, he took part in this year's two races of the Radical European Masters.
2013 Stoneman returned permanently back into the automotive racing. He went to for Redline Racing in the British Porsche Carrera Cup and was five wins fifth overall. Only the Master, Michael Meadows, had won more races. In November, he also made his comeback in Formula racing. In Koiranen GP he received a cockpit for the final race weekend of the GP3 series. The objective of the mission was to question whether Stoneman should continue his career in Formula racing or GT racing. From his team no results was expected of him. Nevertheless, we succeeded Stoneman in the first race with a sixth place points to achieve. In the second race he was in second place even on the podium. In the subsequent test runs after the season Stoneman posted a fastest time. In the GP3 Series season 2014 Stoneman takes for Marussia Manor Racing and thus returns full time back into formula racing.
- 2002-2006: Karting
- 2006: Formula Renault BARC
- 2006: British Formula Renault Winter Series ( No. 19 )
- 2007: BARC Formula Renault (2nd place)
- 2007: British Formula Renault Winter Series ( 6th place)
- 2008: British Formula Renault (4th place )
- 2008: British Formula Renault Winter Series ( 3rd place)
- 2009: British Formula Renault (4th place )
- 2010: Formula 2 (Master)
- 2010: Formula Renault 3.5 (ranked 26)
- 2012: Radical European Masters ( 15th place)
- 2013: British Porsche Carrera Cup ( 5th place)
- 2013: GP3 Series ( 16th place)
- 2014: GP3 Series