Problem: Cronin was born in Cardross, Dunbartonshire, Scotland, the only child of a Protestant mother, Jessie Cronin (nee Montgomerie), and a Catholic father, Patrick Cronin. Cronin often wrote of young men from similarly mixed backgrounds. His paternal grandparents had emigrated from County Armagh, Ireland, and become glass and china merchants in Alexandria. Owen Cronin, his grandfather, had had his surname changed from Cronague in 1870.

The Citadel (1937), a tale of a mining company doctor's struggle to balance scientific integrity with social obligations, helped to incite the establishment of the National Health Service (NHS) in the United Kingdom by exposing the inequity and incompetence of medical practice at the time. In the novel Cronin advocated a free public health service in order to defeat the wiles of those doctors who "raised guinea-snatching and the bamboozling of patients to an art form." Dr Cronin and Aneurin Bevan had both worked at the Tredegar Cottage Hospital in Wales, which served as one of the bases for the NHS. The author quickly made enemies in the medical profession, and there was a concerted effort by one group of specialists to get The Citadel banned. Cronin's novel, which was the highest-selling book ever published by Victor Gollancz, informed the public about corruption within the medical system, planting a seed that eventually led to reform. Not only were the author's pioneering ideas instrumental in the creation of the NHS, but the historian Raphael Samuel asserted in 1995 that the popularity of Cronin's novels played a substantial role in the Labour Party's landslide victory in 1945. By contrast, according to one of Cronin's biographers, Alan Davies, the book's reception was mixed. A few of the more vociferous medical practitioners of the day took exception to one of its many messages: that a few well-heeled doctors in fashionable practices were ripping off their equally well-off patients. Some pointed to the lack of balance between criticism and praise for hard-working doctors. The majority accepted it for what it was, a topical novel. The press attempted to incite passions within the profession in an attempt to sell copy, while Victor Gollancz followed suit in an attempt to promote the book, all overlooking the fact that it was a work of fiction, not a scientific piece of research, and not autobiographical. In the United States The Citadel won the National Book Award, Favorite Fiction of 1937, voted by members of the American Booksellers Association. According to a Gallup poll conducted in 1939, The Citadel was voted the most interesting book readers had ever read.

Did he go on to write any more books?

Answer with quotes:

Question:
Donald Christopher Barber (born 17 April 1930) is an English jazz musician, best known as a bandleader and trombonist. As well as scoring a UK top twenty trad jazz hit, he helped the careers of many musicians, notably the blues singer Ottilie Patterson, who was at one time his wife, and vocalist/banjoist Lonnie Donegan, whose appearances with Barber triggered the skiffle craze of the mid-1950s and who had his first transatlantic hit, "Rock Island Line", while with Chris Barber's band. His providing an audience for Donegan and, later, Alexis Korner makes Barber a significant figure in the British rhythm and blues and "beat boom" of the 1960s.
Barber and Monty Sunshine (clarinet) formed a band in 1953, calling it Ken Colyer's Jazzmen to capitalise on their trumpeter's recent escapades in New Orleans: the group also included Donegan, Jim Bray (bass), Ron Bowden (drums) and Barber on trombone. The band played Dixieland jazz, and later ragtime, swing, blues and R&B. Pat Halcox took over on trumpet in 1954 when Colyer moved on after musical differences and the band became "The Chris Barber Band". In April 1953 the band made its debut in Copenhagen, Denmark. There Chris Albertson recorded several sides for the new Danish Storyville label, including some featuring only Sunshine, Donegan and Barber on double bass. In 1959 the band's version of Sidney Bechet's "Petite Fleur", a clarinet solo by Monty Sunshine with Barber on string bass, spent twenty-four weeks in the UK Singles Charts, making it to No. 3 and selling over one million copies, and was awarded a gold disc. After 1959 he toured the United States many times (where "Petite Fleur" charted at #5). In the late 1950s and early 1960s Barber was mainly responsible for arranging the first UK tours of blues artists Big Bill Broonzy, Sonny Terry and Brownie McGhee and Muddy Waters. This, with the encouragement of local enthusiasts such as Alexis Korner and John Mayall, sparked young musicians such as Peter Green, Eric Clapton and the Rolling Stones. British rhythm and blues powered the British invasion of the USA charts in the 1960s, yet Dixieland itself remained popular: in January 1963 the British music magazine, NME reported the biggest trad jazz event in Britain at Alexandra Palace. It included George Melly, Diz Disley, Acker Bilk, Alex Welsh, Kenny Ball, Ken Colyer, Sunshine, Bob Wallis, Bruce Turner, Mick Mulligan and Barber. Barber stunned traditionalists in 1964 by introducing blues guitarist John Slaughter into the line up who, apart from a break between April 1978 and August 1986, when Roger Hill took over the spot, played in the band until shortly before his death in 2010. Barber next added a second clarinet/saxophone and this line-up continued until 1999. Then Barber added fellow trombonist/arranger Bob Hunt and another clarinet and trumpet. This eleven-man "Big Chris Barber Band" offered a broader range of music while reserving a spot in the programme for the traditional six-man New Orleans line-up. A recording of the Lennon-McCartney composition "Catswalk" can be heard, retitled "Cat Call", on The Songs Lennon and McCartney Gave Away. Written by Paul McCartney the song was recorded in late July 1967 and released as a single in the UK on 20 October 1967.
Answer this question using a quote from the text above:

Who wrote it

Answer:
Paul McCartney