Question: Do Arthur Koestler and Philip Larkin share the same nationality?

Context articles: Stranger on the Square
Arthur Koestler: The Story of a Friendship
Philip Larkin
The Encyclopœdia of Sexual Knowledge
Selected Letters of Philip Larkin, 1940–1985
Arthur Koestler
Holon (philosophy)
Living with Koestler
Relationships that influenced Philip Larkin
Arthur Koestler (book)

Stranger on the Square is the third volume of Arthur Koestler's autobiography, published posthumously in 1984.
 It was co-authored with his wife Cynthia Koestler, née Jefferies, and includes autobiographical notes of her as well.
 The book was published by Hutchinson, London 1984, 242 pages including Index.
 ISBN  .
 It was edited by Harold Harris, who wrote the Introduction and Epilogue.
 He was Koestler's editor for many years.
 The book is illustrated with seven monochrome photographs plus a colour and another momochrome photograph on the dustcover.
Arthur Koestler: The Story of a Friendship is a book by George Mikes published in 1983, soon after Arthur Koestler’s suicide.
 As the author states in the Introduction, the book is not a biography of the subject but a series of recollections and anecdotes of a friendship spanning more than thirty years from 1952 up to the time of Koestler’s suicide in March 1983.
Philip Arthur Larkin (9 August 1922 – 2 December 1985) was an English poet, novelist and librarian.
 His first book of poetry, "The North Ship", was published in 1945, followed by two novels, "Jill" (1946) and "A Girl in Winter" (1947), and he came to prominence in 1955 with the publication of his second collection of poems, "The Less Deceived", followed by "The Whitsun Weddings" (1964) and "High Windows" (1974).
 He contributed to "The Daily Telegraph" as its jazz critic from 1961 to 1971, articles gathered in "All What Jazz: A Record Diary 1961–71" (1985), and he edited "The Oxford Book of Twentieth Century English Verse" (1973).
 His many honours include the Queen's Gold Medal for Poetry.
 He was offered, but declined, the position of Poet Laureate in 1984, following the death of Sir John Betjeman.
The Encyclopaedia of Sexual Knowledge, under the editorship of Dr. Norman Haire (1892–1952), is the first of a trilogy of sexual encyclopaedias by Arthur Koestler writing under the pen name of ‘Dr. A. Costler’.
 It is the English version, published by Koestler's cousin Francis Aldor in 1934, of the book "L'encyclopédie de la vie sexuelle" that Koestler in 1933 wrote, together with "A. Willy" (the pseudonym of his other cousin Willy Aldor) and the German Dr. Levy-Lenz.
 The second book is "Sexual Anomalies and Perversions, Physical and Psychological Development, Diagnoses and Treatment".
 The title of the third book is, in the original French edition of 1939, "L’Encyclopédie de la famille".
 This third book was subsequently translated into English and published under various titles and with changes to the structure and text of the original edition.
 The name of ‘Dr. Costler’ (or 'A. Coester') as the author or co-author of the book is omitted from later editions.
The Selected Letters of Philip Larkin, 1940–1985 is a volume of Philip Larkin's personal correspondence, compiled by Anthony Thwaite, one of Larkin's literary executors, and published in 1992 by Faber and Faber, seven years after Larkin's death.
 It was followed a year later by "Philip Larkin: A Writer's Life", Larkin's official biography, written by Andrew Motion, Larkin's other literary executor.
Arthur Koestler, ( ; ] ; Hungarian: "Kösztler Artúr" ; 5 September 1905 – 1 March 1983) was a Hungarian-British author and journalist.
 Koestler was born in Budapest and, apart from his early school years, was educated in Austria.
 In 1931 Koestler joined the Communist Party of Germany until, disillusioned by Stalinism, he resigned in 1938.
 In 1940 he published his novel "Darkness at Noon", an anti-totalitarian work that gained him international fame.
 Over the next 43 years, from his residence in Britain, Koestler espoused many political causes, and wrote novels, memoirs, biographies and numerous essays.
 In 1968 he was awarded the Sonning Prize "for [his] outstanding contribution to European culture" and in 1972 he was made a Commander of the Order of the British Empire (CBE).
 In 1976 he was diagnosed with Parkinson's disease and in 1979 with terminal leukaemia.
 In 1983 he and his wife committed suicide at their home in London.
A holon (Greek: "ὅλον, holon" neuter form of "ὅλος, holos" "whole") is something that is simultaneously a whole and a part.
 The word was coined by Arthur Koestler in his book "The Ghost in the Machine" (1967, p. 48).
 Koestler was influenced by two observations in proposing the notion of the holon.
 The first observation was influenced by Herbert A. Simon's parable of the two watchmakers—in which Simon concludes that complex systems evolve from simple systems much more rapidly when there are stable intermediate forms present in the evolutionary process than if they are not present.
 The second observation was made by Koestler himself in his analysis of hierarchies and stable intermediate forms in non-living matter (atomic and molecular structure), living organisms, and social organizations.
 He concluded that, although it is easy to identify sub-wholes or parts, wholes and parts in an absolute sense do not exist anywhere.
 Koestler proposed the word holon to describe the hybrid nature of sub-wholes and parts within in vivo systems.
 From this perspective, holons exist simultaneously as self-contained wholes in relation to their sub-ordinate parts, and as dependent parts when considered from the inverse direction.
Living with Koestler: Mamaine Koestler's Letters 1945–51 is a book about the author Arthur Koestler and Mamaine Paget, Koestler’s second wife.
 More specifically, it is a selected compilation of Mamaine’s letters to her twin sister Celia about her life with Koestler.
 The spontaneous and engaging letters reflect the intensity of her life with Koestler between 1945 and 1951.
Throughout the life of the poet Philip Larkin a number of women had important roles which were notable influences on his poetry.
 Since Larkin's death biographers have highlighted the importance of female relationships on Larkin: when Andrew Motion's biography was serialised in the Independent in 1993, the second instalment of extracts was dedicated to the topic.
 In 1999 Ben Brown's play "Larkin with Women" dramatised Larkin's relationships with three of his lovers, and more recently writers such as Martin Amis have continued to comment on this subject.
"Arthur Koestler" is a book by Mark Levene published in 1984, a year after Arthur Koestler's suicide.
 The book is divided into seven main chapters, of which the first of is a biography and the other six critical essays on each of Koestler's six novels, his stories and his play "Twilight Bar".