He was with HM Treasury from 1970 to 1971, then joined Edward Heath's new Central Policy Review Staff (or "Think Tank") and remained there until the change of government in 1974.
Following the Conservative victory in the general election of 1979, he was briefly at 10 Downing Street,[7] before returning to the Treasury as a Special Advisor to Sir Geoffrey Howe and Nigel Lawson as Chancellors of the Exchequer between 1979 and 1984.
[4] In his memoir Inside the Bank of England, Christopher Dow notes that in 1979 only Ridley was brought into the Treasury as a political advisor, and that he was trusted even though he was not a monetarist.
After leaving Hambros, he was a non-executive director of Leopold Joseph Holdings from 1998 to 2004, of Morgan Stanley Bank International from 2006 to 2013, and of Hampden Agencies Ltd from 2007 to 2012, and then of several Equitas insurance companies from 2009 to date.
[4][10] He served on the National Lottery Charities Board from 1994 to 2000, most of that time as its Deputy chairman, and since 2003 has been a member of the Council of the British School at Athens.