Question: Round the Horne co-starred which English actor?

Context articles: Round the Horne
Kenneth Williams
David Leon
Kenneth Horne
Mathew Horne
Stephen Critchlow
Stephen Fry bibliography and filmography
Hugh Paddick
Beyond Our Ken
Rambling Syd Rumpo

Round the Horne is a BBC Radio comedy programme that was transmitted in four series of weekly episodes from 1965 until 1968.
 The series was created by Barry Took and Marty Feldman, with others contributing to later series after Feldman returned to performing, and starred Kenneth Horne, with Kenneth Williams, Hugh Paddick, Betty Marsden and Bill Pertwee.
 The show's announcer was Douglas Smith and from time to time he took part in the sketches.
 It had musical interludes by close harmony singing group the Fraser Hayes Four, and accompaniment by the big band of Edwin Braden ("the great, 'airy fool" according to Kenneth Williams), known as Edwin Braden and the Hornblowers.
 The band was actually the BBC Radio Orchestra but was never billed as such.
 In the fourth series, all the musical duties were performed by the smaller Max Harris Group.
 Took and the cast had worked on the predecessor series "Beyond Our Ken".
 The name is a pun on the nautical phrase for sailing around Cape Horn.
Kenneth Charles Williams (22 February 1926 – 15 April 1988) was an English actor, best known for his comedy roles and in later life as a raconteur and diarist.
 He was one of the main ensemble in 26 of the 31 "Carry On" films, and appeared in many British television programmes and radio comedies, including series with Tony Hancock and Kenneth Horne.
David Jeremy Leon (born 24 July 1980) is an English actor, director, writer and producer.
 As an actor, he is best known for appearing in photographer Rankin's directoral debut "Lives of the Saints" as Othello and Guy Ritchie's film "RocknRolla".
 From 2011 to 2014, he co-starred with Brenda Blethyn in the ITV detective series "Vera."
 Leon has directed several short films "Father", "Man and Boy" and "Orthodox".
 He completed his first feature-length film, also called "Orthodox", in 2015.
Charles Kenneth Horne, generally known as Kenneth Horne, (27 February 1907 – 14 February 1969) was an English comedian and businessman.
 He is perhaps best remembered for his work on three BBC Radio series: "Much-Binding-in-the-Marsh" (1944–54), "Beyond Our Ken" (1958–64) and "Round the Horne" (1965–68).
Mathew Frazer Horne (born 6 September 1978) is an English actor, comedian, television presenter, and narrator.
 He is best known for appearing on several BBC sketch shows and sitcoms, most notably "Gavin & Stacey" (as Gavin Shipman), "The Catherine Tate Show", "20 Things to do Before You're 30", "Teachers", "Horne and Corden", and "Bad Education".
Stephen Critchlow is an English actor, notable for his work in the theatre and appearances on radio series such as "Truly, Madly, Bletchley", "The Way We Live Right Now" and "Spats", along with radio episodes of "Torchwood" ("Lost Souls") and "Doctor Who" ("The Nowhere Place").
 He has also appeared in "" as Kenneth Horne and is currently appearing in the West End version of "The 39 Steps".
Stephen Fry is an English actor, comedian, author and television presenter.
 With Hugh Laurie, as the comedy double act Fry and Laurie, he co-wrote and co-starred in "A Bit of Fry and Laurie", and the duo also played the title roles in "Jeeves and Wooster".
 Fry played the lead in the film "Wilde", was Melchett in the "Blackadder" television series and is the host of celebrity comedy trivia show, "QI".
 He has contributed columns and articles for newspapers and magazines, and has written four novels and three autobiographies, "Moab Is My Washpot", "", and "More Fool Me: A Memoir".
Hugh William Paddick (22 August 1915 – 9 November 2000) was an English actor, whose most notable role was in the 1960s BBC radio show "Round the Horne", in sketches such as "Charles and Fiona" (as Charles) and "Julian and Sandy" (as Julian).
 Both he and Kenneth Williams are largely responsible for introducing the underground language polari to the British public.
Beyond Our Ken (1958–1964) is a radio comedy programme, the predecessor to "Round the Horne" (1965–1968).
 Both programmes starred Kenneth Horne, Kenneth Williams, Hugh Paddick, Betty Marsden and Bill Pertwee, with announcer Douglas Smith.
 Musical accompaniment was provided by the BBC Revue Orchestra.
 The name is a pun on Kenneth Horne's name and the (now mainly Northern English and Scots) word "", meaning "knowledge or perception".
Rambling Syd Rumpo was a folk singer character, played by the English comedian and actor Kenneth Williams, originally in the 1960s BBC Radio comedy series "Round the Horne".