Question: Barry Hines helped adapt his novel for which 1969 drama film?

Context paragraphs:
A Kestrel for a Knave: A Kestrel for a Knave is a novel by English author Barry Hines, published in 1968.  It is set in a mining area (only ever referred to as "the City") and tells of Billy Casper, a young working class boy troubled at home and at school, who only finds solace when he finds and trains a kestrel whom he names "Kes".

The Body Snatcher (film): The Body Snatcher is a 1945 horror film directed by Robert Wise based on the short story "The Body Snatcher" by Robert Louis Stevenson.  The film's producer Val Lewton helped adapt the story for the screen, writing under the pen name of "Carlos Keith".  The film was marketed with the tagline "The screen's last word in shock sensation!"  The frequent mentions of Burke, Hare, and Dr. Knox, all refer to the West Port murders in 1828.

Threads: Threads is a 1984 British television drama jointly produced by the BBC, Nine Network and Western-World Television Inc.  Written by Barry Hines and directed by Mick Jackson, it is a docudrama account of nuclear war and its effects on the city of Sheffield in Northern England.  The plot centres on two families as a confrontation between the United States and the Soviet Union erupts.  As the nuclear exchange between NATO and the Warsaw Pact begins, the film depicts the medical, economic, social and environmental consequences of nuclear war.

Barry Hines: Melvin Barry Hines, FRSL (30 June 1939 – 18 March 2016) was an English author who wrote several popular novels and television scripts.  He is best known for the novel "A Kestrel for a Knave" (1968), which he helped adapt for Ken Loach's film "Kes" (1969).

Rita May (actress): May began her career as a singer on the working men's club circuit in and around South Yorkshire.  She featured in the television adaptation of Barry Hines' "The Price of Coal", a "Play for Today" first broadcast in 1977, and as Jimmy Kemp's mother in the Hines' scripted nuclear war drama "Threads" (1984).  She has appeared in popular television series such as "Early Doors" and "Drop Dead Gorgeous", and radio programmes including "Ed Reardon's Week" and "The Blackburn Files".  In 2005, she appeared in one episode of "Heartbeat".  In March 2009, it was announced that from 17 April she would appear as Connie Rathbone, a new love interest of pigeon fancier Jack Duckworth, in the ITV1 soap opera "Coronation Street".  She had already appeared in the soap opera in 'bit parts' on three earlier occasions.

Brave Records of the Sanada Clan: Brave Records of the Sanada Clan (真田風雲録 , Sanada fūunroku ) is a Japanese film directed by Tai Kato in 1963.  It is a jidaigeki musical about Sasuke Sarutobi and the Sanada Ten Braves who, under the leadership of Yukimura Sanada, try to defend Toyotomi Hideyori during the siege of Osaka Castle by the Tokugawa armies.  Yoshiyuki Fukuda helped adapt his own stage play for the screen.

The Price of Coal: The Price of Coal is a two-part television drama written by Barry Hines and directed by Ken Loach first broadcast as part of the "Play for Today" series in 1977.  Set at the fictional Milton Colliery, near Barnsley in South Yorkshire, the episodes contrast "efforts made to cosmetically improve the pit in preparation for a royal visit (part one) and the target-conscious safety shortcuts that precipitate a fatal accident (part two)."

Looks and Smiles: Looks and Smiles is a 1981 British drama film directed by Ken Loach.  It is based on the novel of the same name, written by Barry Hines.  The film was entered into the 1981 Cannes Film Festival, where Loach won the Young Cinema Award.

The Gamekeeper (film): The Gamekeeper is a 1980 British drama film directed by Ken Loach.  It is based on a novel of the same name by Barry Hines.  It competed in the Un Certain Regard section at the 1980 Cannes Film Festival.

Kes (film): Kes is a 1969 drama film directed by Ken Loach and produced by Tony Garnett.  The film is based on the 1968 novel "A Kestrel for a Knave", written by the Barnsley-born author Barry Hines.  The film is ranked seventh in the British Film Institute's Top Ten (British) Films and among the top ten in its list of the 50 films you should see by the age of 14.

Supporting paragraphs: Barry Hines Kes (film)
Answer: Kes