He has been a non-executive director at Horizon Nuclear Power since October 2014.
Stone also holds academic posts as a visiting professor at University College London's International Energy Policy Institute in Adelaide, Australia since May 2012 and at the Infrastructure Investment and Finance in the Bartlett School since 2010. 
Big Four adviser
During his time as a government adviser Stone was global senior adviser at KPMG Corporate Finance from 2011 until 2013.
He was previously the founder and former chair of KPMG's global infrastructure and project group (1997-2011) and was also a non-executive director at Anglian Water from October 2011  until June 2015.
UK is best destination for new nuclear investors
According to the minutes of the May 2012 meeting of the Nuclear Development Forum:
- Dr Tim Stone agreed that the UK was the best destination for investors in new nuclear and would lead to the creation of high quality jobs. The first Japanese prefecture has agreed to restart a reactor and hoped this would lead to more positive new stories. Following a trip to China, he remarked that programme management was a big challenge for the new nuclear programme. In China he was impressed to see that construction was to time and budget and expressed confidence that the UK could do the same.
- Director S. G. Warburg and Co., Ltd. (1989 – 1995)
- Managing director, Chase Manhattan Corporation (1983 – 1989)
- Senior manager Arthur Andersen and Co., Ltd (1976 – 1983)
- Expert of the Board, European Investment Bank, Luxembourg since 2003.