Question: What English zoo owner and gambling club host purchased Howletts Zoo in 1973?

Context paragraphs:
John Aspinall (zoo owner): John Victor Aspinall (11 June 1926 – 29 June 2000) was an English zoo owner and gambling club host.  From middle class beginnings he used gambling to move to the centre of British high society in the 1960s.  He was born in Delhi during the British Raj, and was a citizen of the United Kingdom.

Garrard Tyrwhitt-Drake: Sir (Hugh) Garrard Tyrwhitt-Drake {'1': ", '2': ", '3': ", '4': "} (22 May 1881 – 24 October 1964) was a businessman, zoo owner and author.  Between 1915 and 1950, he was twelve times the Mayor of Maidstone, Kent and was High Sheriff of Kent in 1956–57.

Aviation Club de France: Aviation Club de France was a gambling club in central Paris, France.

Edward Cross (zoo proprietor): Edward Cross ("baptised" 3 February 1774 – 26 September 1854) was an English zoo proprietor and dealer in animals.

My Steve: My Steve is a biographical account of Terri Irwin's life with her late husband, the zoo owner and television personality Steve Irwin.  It was published by Simon & Schuste Australia.

Port Lympne Mansion: Port Lympne, at Lympne, Kent is an early 20th-century country house built for Sir Philip Sassoon by Herbert Baker and Philip Tilden.  Completed after the First World War.  Following Sassoon's death in 1939 it was bequeathed with its contents, including cars and planes, to Hannah Gubbay, his cousin.  It was abandoned after the Second World War.  In 1973, it was purchased by John Aspinall as part of an expansion of his Howletts Zoo.  The house is a Grade II* listed building as of 29 December 1966.

The Aspinall Foundation: The Aspinall Foundation (formerly The John Aspinall Foundation) is a British charity (Registered Charity 326567) which works to promote wildlife conservation.  It was set up by professional gambler and zoo owner John Aspinall in 1984 and runs the two zoos he set up, Port Lympne Wild Animal Park and Howletts Wild Animal Park in Kent, England.  It also supports a number of conservation projects overseas to protect endangered species.  The charity is now run by John's son, Damian Aspinall.

Abahani Limited (Chittagong): Chittagong Abahani Limited (Bengali: আবাহনী লিমিটেড ) is a sports club in Bangladesh. The club was established at Dhaka in 1972 through reorganisation of Iqbal Sporting Club.  Within a short time, the club gained fame through commendable performances in hockey, cricket and football tournaments.  A wing of Abahani Limited was established in Chittagong known as Chittagong Abahani.  It is currently a team of Bangladesh Premier League. <br>The team was relegated from Bangladesh Premier League in 2010–11 season.  It again gained the promotion to Premier League by becoming champion of 2013 Bangladesh Championship League.  The club host Sheikh Kamal International Club Cup tournament every year in memories of their founder.  They won the inaugural edition of the tournament in 2015.  The club won their first major domestic trophy in 2016 by winning 2016 Independence Cup under guidance of Slovakian coach Jozef Pavlik.

Howletts Wild Animal Park: Howletts Wild Animal Park (formerly known as Howletts Zoo) was set up as a private zoo in 1957 by John Aspinall near Canterbury, Kent.  The animal collection was opened to the public in 1975.  To give more room for the animals another estate at Port Lympne near Hythe, Kent was purchased in 1973, and opened to the public as Port Lympne Zoo in 1976.

William Crockford: William Crockford (1776–1844) was an English Regency entrepreneur; horse racing enthusiast and proprietor of the infamous gambling club Crockford's who became one of the richest men in England.

Supporting paragraphs: Port Lympne Mansion John Aspinall (zoo owner)
Answer: John Aspinall