Question: Who wrote the screenplay for the film in which Mark Lester played the title role?

Context paragraphs:
Melody (1971 film): Melody is a 1971 British film directed by Waris Hussein about puppy love.  It was released as S.W.A.L.K. in the United Kingdom (S.W.A.L.K. is a message traditionally written on the envelopes of love letters by British schoolchildren, standing for "sealed with a loving kiss").  The film starred Jack Wild, Mark Lester and Tracy Hyde.  Although the film was a box office disappointment in both the United States and Britain, it turned out to be an enormous hit in Japan as well as in some Latin American countries such as Argentina and Chile, and a modest hit in South Africa.

Oliver! (film): Oliver!  is a 1968 British musical drama film directed by Carol Reed and based on the stage musical of the same name, with book, music and lyrics written by Lionel Bart.  The screenplay was written by Vernon Harris.

What the Peeper Saw: Night Hair Child (also released under the titles Night Child, Child of the Night, What the Peeper Saw, Tua Presenza Nuda and Diabólica Malicia) is a 1971 horror film starring Mark Lester, Britt Ekland, Hardy Krüger and Lilli Palmer.  The film was directed by James Kelley (who is better known for directing "The Beast in the Cellar").  The Italian version of the film credits Andrea Bianchi as director, under the pseudonym Andrew White.

Emanuelle and the Last Cannibals: Emanuelle and the Last Cannibals (Italian: "Emanuelle e gli Ultimi Cannibali" ) is an Italian sexploitation-cannibal film directed by Joe D'Amato.  The film involves Emanuelle (Laura Gemser) a photojournalist who discovers a woman in a mental hospital who is a cannibal and features tattoos of an Amazonian tribe on her skin.  Along with Professor Mark Lester (Gabriele Tinti), the two travel to Africa with a team to discover the source of long-thought-extinct tribe that practices cannibalism.

Class of 1984: Class of 1984 is a 1982 Canadian-American action crime thriller film directed by Mark Lester and co-written by Tom Holland and John Saxton based on a story by Holland.  The film stars Perry King, Merrie Lynn Ross, Timothy Van Patten, Stefan Arngrim, Michael J. Fox (credited as Michael Fox in an early role shortly before his breakthrough on the TV series "Family Ties"), and Roddy McDowall.

The Music Hall Guild of Great Britain and America: The Music Hall Guild of Great Britain and America and the Theatre and Film Guild of Great Britain and America is a registered theatre charity and non-profit making theatre organisation based in London.  The Guild's patrons include Brian Croucher, Anita Dobson, Fenella Fielding, Sheila Ferguson, Jessica Martin, Lorraine Chase, Gillian Gregory, Mark Lester, Jessie Wallace, Barbara Windsor and Shani Wallis.

The Prince and the Pauper (1977 film): The Prince and the Pauper (US title: Crossed Swords) is a 1977 action adventure film directed by Richard Fleischer, based on "The Prince and the Pauper" by Mark Twain.  It stars Mark Lester, Oliver Reed, Ernest Borgnine, Raquel Welch, George C. Scott, Charlton Heston and Sir Rex Harrison.

Mark Lester: Mark Lester (born Mark A. Letzer; 11 July 1958) is an English former child actor known for playing the title role in the 1968 musical film version of "Oliver! " and starring in a number of other British and European films of the 1960s and 1970s and in a number of television series.

Run Wild, Run Free: Run Wild, Run Free is a 1969 British drama film directed by Richard C. Sarafian and starring John Mills and Mark Lester.  The film was written by David Rook, based on his novel "The White Colt", and shot on location in Dartmoor, Devon, England.

Our Mother's House: Our Mother's House is a 1967 British drama film, directed by Jack Clayton.  It nominally stars Dirk Bogarde (who only appears in the film's second half) and principally features a cast of seven juvenile actors, including Pamela Franklin, Phoebe Nicholls and Mark Lester, with popular British actress Yootha Joyce in a supporting role.  The screenplay was written by Jeremy Brooks and Haya Harareet, based on the 1963 novel of the same name by Julian Gloag.

Supporting paragraphs: Mark Lester Oliver! (film)
Answer: Vernon Harris