The Principal Private Secretary to the Prime Minister is a senior official in the British Civil Service who acts as Principal Private Secretary to the Prime Minister of the United Kingdom.
 The holder of this office is traditionally the head of the Prime Minister's Office.
 In the Civil Service, the role is currently graded as a Director-General.
 To date, no woman has ever occupied the office.
 In fiction, the character of Bernard Woolley in the television series "Yes, Prime Minister", occupied this post.
Sir Samuel Knox Cunningham, 1st Baronet, QC (3 April 1909 – 29 July 1976) was a Northern Irish barrister, businessman and politician.
 As an Ulster Unionist politician at a time when the Unionists were part of the Conservative Party, he was also a significant figure in United Kingdom politics as Parliamentary Private Secretary to Harold Macmillan.
 His nephew was Sir Josias Cunningham.
Christopher James Skidmore, {'1': ", '2': ", '3': ", '4': "} (born 17 May 1981) is a British politician, author, and historian.
 He has served since 2010 as the Conservative Member of Parliament (MP) for Kingswood, South Gloucestershire, and in 2015 became Parliamentary Private Secretary to the Chancellor of the Exchequer.
 When Theresa May became Prime Minister in 2016 he was appointed Parliamentary Secretary at the Cabinet Office, where he is described as Minister for the Constitution.
The later life of Winston Churchill documents the life of the British statesman from the end of World War II and his second term as Prime Minister of the United Kingdom, until his subsequent death and funeral in 1965.
 After the end of the war Churchill had to step down as Prime Minister of the United Kingdom because the Conservative Party lost the 1945 election.
 For six years he was to serve as the Leader of the Opposition.
 During these years Churchill continued to influence world affairs; in 1946 he gave his Iron Curtain speech which spoke of the expansionist policies of the USSR and the creation of the Eastern Bloc; Churchill also argued strongly for British independence from the European Coal and Steel Community (which he saw as a Franco-German project as Britain still had an empire).
 In the General Election of 1951 Labour was defeated and Churchill became Prime Minister for a second time.
 Churchill continued to lead Britain but was to suffer increasingly from health problems.
 Aware that he was slowing down both physically and mentally he resigned from the Cabinet in 1955.
 However he continued to sit as an MP for Woodford until he retired from politics in 1964.
 Churchill died on 24 January 1965 and was granted the honour of a state funeral.
 He was buried in his family plot in St Martin's Church, Bladon near to where he was born at Blenheim Palace.
Caroline Julia Dinenage (born 28 October 1971) is an English Conservative Party politician who was elected as Member of Parliament (MP) for Gosport at the 2010 general election.
 She was re-elected in 2015 and 2017.
 In July 2014, she was appointed as Parliamentary Private Secretary (PPS) to the Minister for Women and Equalities, Nicky Morgan.
 In May 2015, Dinenage was appointed to the dual roles of Parliamentary Under Secretary of State at the Ministry of Justice and Minister for Women and Equalities at the Department for Education.
 In July 2016, Dinenage was appointed Parliamentary Under Secretary of State for Women, Equalities and Early Years at the Department for Education.
The Barran Baronetcy, of Chapel Allerton Hall in Chapel Allerton in the West Riding of the County of York and Queen's Gate, St Mary's Abbot, in Kensington in the County of London, is a title in the Baronetage of the United Kingdom.
 It was created on 11 February 1895 for the merchant and Liberal politician John Barran.
 He represented Leeds and Otley in the House of Commons.
 He was succeeded by his grandson, the second Baronet.
 He sat as Liberal Member of Parliament for Hawick and served as Parliamentary Private Secretary to Prime Minister H. H. Asquith.
Maurice Harold Macmillan, 1st Earl of Stockton, {'1': ", '2': ", '3': ", '4': "} (10 February 1894 – 29 December 1986) was a British statesman of the Conservative Party who served as Prime Minister of the United Kingdom from 1957 to 1963.
 Nicknamed "Supermac", he was known for his pragmatism, wit and unflappability.
Sir Desmond Angus Swayne, {'1': ", '2': ", '3': ", '4': "} (born 20 August 1956) is a Conservative Party politician in the United Kingdom.
 He is the Member of Parliament for the constituency of New Forest West in Hampshire.
 He was formerly also Parliamentary Private Secretary to the Prime Minister, David Cameron, having been his PPS during his time as Leader of the Opposition, 2005–10, prior to his appointment in September 2012 to the office of Lord Commissioner of HM Treasury.
 In June 2016, it was announced Swayne would receive a knighthood in the Queen's Birthday Honours for political service.
Justin Paul Tomlinson (born 5 November 1976) is the Conservative MP for North Swindon.
 He was originally a Conservative Councillor on Swindon Borough Council, being elected in 2000.
 He is the current Member of Parliament for Swindon North.
 He was appointed Parliamentary Under Secretary of State for Disabled People following the 2015 general election victory of the Conservative Party, serving until new Prime Minister Theresa May reshuffled the government in 2016.
 Prior to that he was Parliamentary Private Secretary to Ed Vaizey.
Tessa Jane Munt (born 16 October 1959) is a British Liberal Democrat politician.
 She was the Member of Parliament (MP) for Wells in Somerset from 2010 – 2015 and had previously served as the Parliamentary Private Secretary (PPS) to the Secretary of State for Business, Innovation and Skills, Vince Cable.
 Following the appointment of Jo Swinson as PPS to the Leader of the Liberal Democrats, Nick Clegg, Tessa was appointed as Parliamentary Private Secretary to Liberal Democrat Secretary of State for Business, Innovation and Skills, Vince Cable.

Question: During which years was the British statesman, for which Knox Cunningham was Parliamentary Private Secretary, Prime Minister of the United Kingdom?
Answer: 1957 to 1963