Dr Walker is Chair of the Accountancy and Actuarial Discipline Board (AADB) and an executive director of the UK’s Financial Reporting Council, as well as a Church Commissioner. From October 2000 to September 2005 he served as Director General of the UK’s Health and Safety Executive.
Previously an academic scientist, he has taught physics and chemistry at various universities; worked on trade with the Middle East, telecommunications liberalisation and grants to industry at the Department of Trade and Industry; been principal private secretary to successive Secretaries of State for Trade and Industry; and taken responsibility for civil nuclear matters. Other posts held have been UK Governor of IAEA, Chairman of the EBRD Nuclear Safety Account, Home Office Director General for immigration and nationality; and Deputy Chairman of HM Customs and Excise. He is also a non-executive director in the public and private sectors and a lay member of the Council of Warwick University, as well as a fellow of the Royal Society of Arts.