Question: Which English actor or actress starred in the British musical "Pieces of Eight", and was one of the main ensemble in 26 of the 31 "Carry On" films?

Context paragraphs:
Carry On Emmannuelle: Carry On Emmannuelle is the 30th in the series of "Carry On" films to be made, and was released in 1978.  This was the last "Carry On" film to be made until "Carry On Columbus" in 1992.  The film was to be the final "Carry On" for many regulars, including Kenneth Williams (in his 26th "Carry On"), Kenneth Connor (in his 17th), Joan Sims (in her 24th) and Peter Butterworth (in his 16th).  Jack Douglas and Jim Dale are the only regulars from the original run of Carry On films to bridge the gap to "Carry On Columbus".  Beryl Reid and Suzanne Danielle make their only appearances in the series here.  The film featured a change in style, becoming more openly sexual.  This was highlighted by the implied behaviour of Danielle's character, though she does not bare any more flesh than any other "Carry On" female lead.  These changes brought the film closer to the then popular series of X-rated "Confessions..." comedies, or indeed the official "Emmanuelle" films it parodies.  This, and "Carry On England", were the only films in the series to be certified AA by the then British Board of Film Censors, which restricted audiences to those aged 14 and over.

Royce Pierreson: Royce Pierreson (born April 2, 1990) is a British actor, known for his role as Reece in "Murdered by My Boyfriend."  He appears as part of the main ensemble in the fourth season of "Line of Duty."

Carry On Cleo: Carry On Cleo is a British film comedy which was released in 1964.  It is the tenth in the series of "Carry On" films to be made, and the website ICONS.a portrait of England describes "Carry On Cleo" as "perhaps the best" of the series.  Regulars Sid James, Kenneth Williams, Kenneth Connor, Charles Hawtrey, and Jim Dale are present and Connor made his last appearance until his return in "Carry On Up the Jungle" six years later.  Joan Sims returned to the series for the first time since "Carry On Regardless" three years earlier.  Sims would now appear in every "Carry On" up to "Carry On Emmannuelle" in 1978, making her the most prolific actress in the series.  The title role is played by Amanda Barrie in her second and last Carry On.  Along with "Carry On Sergeant" and "Carry On Screaming! ", its original posters were reproduced by the Royal Mail on stamps to celebrate the 50th anniversary of the Carry on series in June 2008.

Kenneth Williams: 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.

Pieces of Eight (1959 revue): Pieces of Eight was a British musical comedy revue with sketches written by Peter Cook, music by Laurie Johnson and starring Kenneth Williams and Fenella Fielding.

Kenneth Alwyn: Kenneth Alwyn (born Kenneth Alwyn Wetherell, 28 July 1925) is an English conductor, composer and writer.  Described by BBC Radio 3 as "one of the great British musical directors", Alwyn is known for his many recordings, including with the London Symphony Orchestra on Decca’s first stereophonic recording of Tchaikovsky’s "1812 Overture".  He is also known for his long association with BBC Radio 2’s orchestral live music programme "Friday Night is Music Night", appearing for thirty years as a conductor and presenter, and for his contribution to British musical theatre as a prolific musical director in the 1950s and 1960s.  He is a Fellow of the Royal Academy of Music and is married to the actress Mary Law.

Hugh Futcher: Hugh Futcher (born 29 October 1937 in Portsmouth, Hampshire) is an English actor in theatre, television and film.  He was a member of the stock company of the Carry On films, with notable parts in "Carry On Spying", "Carry On at Your Convenience", and "Carry On Behind".  Other films include Roman Polanski's "Repulsion" (as Colin's pubmate Reggie) and the Herman's Hermits musical "Mrs. Brown, You've Got a Lovely Daughter".

Cinema Verite (2011 film): Cinema Verite is a 2011 HBO drama film directed by Shari Springer Berman and Robert Pulcini.  The film's main ensemble cast starred Diane Lane, Tim Robbins, James Gandolfini and Patrick Fugit.  The film follows a fictionalized account of the production of "An American Family", a 1973 PBS documentary television series that is said to be one of the earliest examples of the reality television genre.  Principal photography was completed in Southern California.  The film premiered on April 23, 2011.

The One Ensemble of Daniel Padden: The One Ensemble is a British musical group, based in Glasgow.  The project was initially conceived by Volcano The Bear member Daniel Padden as a vehicle for his solo work, and their first three albums were released under the name "The One Ensemble Of Daniel Padden".  Two studio albums in this mould were released, an eponymous debut on the Catsup Plate label in 2003 and "The Owl Of Fives" on Textile Records in 2004.  Although mostly recorded by Padden on his own, these albums featured contributions from other musicians including Jeremy Barnes, Alex Neilson and David Keenan.

James Marsden: James Paul Marsden (born September 18, 1973) is an American actor, singer and former Versace model.  Marsden began his acting career guest-starring in television shows "", "Touched by an Angel," and "Party of Five".  He gained prominence with his portrayal of Scott Summers/Cyclops in the "X-Men" film series and starred in 2006's "Superman Returns".  Since 2016, Marsden has starred as gunslinger Teddy Flood, a sentient android, in the HBO science fiction-western thriller series "Westworld", as part of the main ensemble.

Supporting paragraphs: Pieces of Eight (1959 revue) Kenneth Williams
Answer: Kenneth Williams