Question: Who is the English impressionist and comedian that Billy Marsh represents?

Context paragraphs:
William Edward Love: William Edward Love (1806–1867) was an English impressionist.

Billy Marsh: William Rawlinson "Billy" Marsh (1917 – 19 December 1995) was a British theatrical agent.  Widely known as the “doyen of theatrical agents”, he was the founder and namesake of Billy Marsh Associates, a renowned entertainment agency, in recent times representing the likes of Jon Culshaw, Esther Rantzen and Fiona Phillips.  He is the only theatrical agent ever to be subject of the BBC biographical documentary series "This Is Your Life".

The Terrace at Saint-Germain, Spring (painting): The Terrace at Saint-Germain, Spring is a painting by English Impressionist painter, Alfred Sisley, completed in 1875.  It is in The Walters Art Museum collection.

Wynford Dewhurst: Wynford Dewhurst, R.B.A. (Manchester, 26 January 1864 – 9 July 1941, Burton upon Trent) was an English Impressionist painter and notable art theorist.  He spent considerable time in France and his work was profoundly influenced by Claude Monet.

Arthur Diehl: Arthur Vidal Diehl (1870 – 12 January 1929) was a prominent English impressionist landscape artist.

Sam Jones III: Samuel L. Jones III (born April 29, 1983), better known as Sam Jones III, is an American actor, best known for playing Pete Ross on the first three seasons of the Superman television series "Smallville", Willie Worsley in the 2006 film "Glory Road" , Craig Shilo on "Blue Mountain State", Chaz Pratt on "ER" and Billy Marsh in the 2006 film ""Home of the Brave".

Jon Culshaw: Jonathan Peter "Jon" Culshaw (born 2 June 1968) is an English impressionist and comedian, best known for his work on the radio comedy "Dead Ringers" since 2000.

Frederick Hall (painter): Frederick Hall (6 February 1860 – 21 August 1948), often known as (and signing his work as) Fred Hall, was an English impressionist painter of landscapes, rustic subjects, and portraits who exhibited at the Royal Academy and the Paris Salon, where he was awarded a gold medal in 1912.  He was an important member of the Newlyn School, in Cornwall, and is notable for both his series of witty caricatures of his fellow Newlyn artists (including Frank Bramley, Stanhope Forbes, and Norman Garstin) and his artistic development away from the strict realism of the Newlyn School towards impressionism.

Dustin Gee: Gerald Harrison (24 June 1942 – 3 January 1986), who performed under the name Dustin Gee, was an English impressionist and comedian, best known for his double act with fellow comic, Les Dennis.

Alistair McGowan: Alistair Charles McGowan (born 24 November 1964) is an English impressionist, comic, actor, singer and writer best known to British audiences for "The Big Impression" (formerly "Alistair McGowan's Big Impression"), which was, for four years, one of BBC1's top-rating comedy programmes – winning numerous awards, including a BAFTA in 2003.  He has also worked extensively in theatre and appeared in the West End in "Art", "Cabaret", "The Mikado" and "Little Shop of Horrors" (for which he received a "Laurence Olivier Award" nomination).  As a television actor, he played the lead role in BBC1's "Mayo".  He wrote the play "Timing" (nominated as Best New Comedy at the whatsonstage.com awards) and the book "A Matter of Life and Death or How to Wean Your Man off Football" with former comedy partner Ronni Ancona.  He also provided voices for "Spitting Image".

Supporting paragraphs: Billy Marsh Jon Culshaw
Answer: Jon Culshaw