This is a list of 1978 British incumbents.

Government

• Monarch
  • Head of State – Elizabeth II, Queen of the United Kingdom (1952–2022)
• Prime Minister
  • Head of Government – James Callaghan, Prime Minister of the United Kingdom (1976–1979)
• First Lord of the Treasury
  • James Callaghan, First Lord of the Treasury (1976–1979)
• Chancellor of the Exchequer
  • Denis Healey, Chancellor of the Exchequer (1974–1979)
• Second Lord of the Treasury
  • Denis Healey, Second Lord of the Treasury (1974–1979)
• Secretary of State for Foreign and Commonwealth Affairs
  • Dr David Owen, Secretary of State for Foreign and Commonwealth Affairs (1977–1979)
• Secretary of State for the Home Department
  • Merlyn Rees, Secretary of State for the Home Department (1976–1979)
• Secretary of State for Transport
  • Bill Rodgers, Secretary of State for Transport (1976–1979)
• Secretary of State for Scotland
  • Bruce Millan, Secretary of State for Scotland (1976–1979)
• Secretary of State for Social Services
  • David Ennals, Secretary of State for Social Services (1976–1979)
• Secretary of State for Northern Ireland
  • Roy Mason, Secretary of State for Northern Ireland (1976–1979)
• Secretary of State for Defence
  • Frederick Mulley, Secretary of State for Defence (1976–1979)
• Secretary of State for Industry
  • Eric Varley, Secretary of State for Industry (1975–1979)
• Secretary of State for Trade
  1. Edmund Dell, Secretary of State for Trade (1976–1978)
  2. John Smith, Secretary of State for Trade (1978–1979)
• Secretary of State for Education and Science
  • Shirley Williams, Secretary of State for Education and Science (1976–1979)
• Secretary of State for Wales
  • John Morris, Secretary of State for Wales (1974–1979)
• Lord Privy Seal
  • Fred Peart, Baron Peart, Lord Privy Seal (1976–1979)
• Leader of the House of Commons
  • Michael Foot, Leader of the House of Commons (1976–1979)
• Lord President of the Council
  • Michael Foot, Lord President of the Council (1976–1979)
• Lord Chancellor
  • Elwyn Jones, Baron Elwyn-Jones, Lord Chancellor (1974–1979)
• Chancellor of the Duchy of Lancaster
  • Harold Lever, Chancellor of the Duchy of Lancaster (1974–1979)

Religion

• Archbishop of Canterbury
  • Donald Coggan, Archbishop of Canterbury (1974–1980)
• Archbishop of York
  • Stuart Blanch, Archbishop of York (1975–1983)