Fifteen-year-old Billy Casper has little hope in life. He is picked on, both at home by his physically and verbally abusive older half-brother, Jud, and at school, by his schoolmates and by abusive teachers. Although he insists that his earlier petty criminal behavior is behind him, he occasionally steals eggs and milk from milk floats. He has difficulty paying attention in school and is often provoked into tussles with classmates. Billy's father has left the family some time ago, and his mother refers to him at one point, while somberly speaking to her friends about her children and their chances in life, as a "hopeless case."
One day, Billy takes a kestrel from a nest on a farm. His interest in learning falconry prompts him to steal a book on the subject from a secondhand book shop, as he is underage and needs – but lies about the reasons he cannot obtain – adult authorization for a borrower's card from the public library. As the relationship between Billy and "Kes", the kestrel, improves during the training, so does Billy's outlook and horizons. For the first time in the film, Billy receives praise, from his English teacher after delivering an impromptu talk about training Kes.
Jud leaves money and instructions for Billy to place a bet on two horses, but, after consulting a bettor who tells him the horses are unlikely to win, Billy spends the money on fish and chips and intends to purchase meat for his bird (instead the butcher gives him scrap meat free of charge). However, the horses do win. Outraged at losing a payout of more than £10, Jud takes revenge by killing Billy's kestrel. Grief-stricken, Billy retrieves the bird's broken body from the waste bin and, after showing it to Jud and his mother, buries the bird on the hillside overlooking the field where he'd flown.David Bradley as Billy Casper
Freddie Fletcher as Jud
Lynne Perrie as Mrs Casper
Colin Welland as Mr Farthing
Brian Glover as Mr Sugden
Bob Bowes as Mr Gryce
Bernard Atha as Youth employment officer
Joey Kaye as Pub comedian
Robert Naylor as MacDowell
Zoe Sutherland as Librarian
Eric Bolderson as Farmer
Joe Miller as Reg, Mother's Friend
Bill Dean as Fish and Chip Shop Man
Geoffrey Banks as Mathematics teacher
Duggie Brown as Milkman
Trevor Hesketh as Mr Crossley
Harry Markham as Newsagent
John Pollard as Footballing Legend Bremner
Steve Crossland as schoolboy Crossland
Both the film and the book provide a portrait of life in the mining areas of Yorkshire of the time, reportedly the miners in the area were then the lowest paid workers in a developed country. The film was produced during a period when the British coal-mining industry was being run down, as gas and oil were increasingly used in place of coal, which led to wage restraints and widespread pit closures. Shortly before the film's release, the Yorkshire coalfield, where the film was set, was brought to a standstill for two weeks by an unofficial strike.
The film was shot on location, including in St. Helens School, Athersley South, later renamed Edward Sheerien School (demolished in 2011); and in and around the streets of Hoyland and Hoyland Common.
Set in Barnsley, the film contains broad local dialects. The cast have authentic Yorkshire accents and used or knew the dialects. The extras were all hired from in and around Barnsley. The DVD version of the film has certain scenes dubbed over with fewer dialect terms than in the original. In a 2013 interview, director Ken Loach said that, upon its release, United Artists organised a screening of the film for some American executives and they said that they could understand Hungarian better than the dialect in the film.
The production company was set up with the name "Kestrel Films". Ken Loach and Tony Garnett used this for some of their later collaborations such as Family Life and The Save the Children Fund Film.
The certificate given to the film has occasionally been reviewed by the British Board of Film Classification, as there is a small amount of swearing, including more than one instance of the word twat. It was originally classified as Universal, at a time when the only other certificates were Adult and X. Three years later, Stephen Murphy, the BBFC Secretary, wrote in a letter that it would have been given the new Advisory certificate under the system then in place. Murphy also argued that the word "bugger" is a term of affection and not considered offensive in the area that the film was set. In 1987, the VHS release was given a PG certificate on the grounds of "the frequent use of mild language", and the film has remained PG since that time.
The film was a word of mouth hit in Britain, eventually making a profit. However it was a commercial flop in the US. In his four-star review, Roger Ebert said that the film failed to open in Chicago, and attributed the problems to the Yorkshire accents. Ebert saw the film at a 1972 showing organised by the Biological Honor Society at the Loyola University Chicago, which led him to ask, "were they interested in the movie, or the kestrel?"
The film has universal acclaim and currently holds a score of 100% on Rotten Tomatoes.
Director Krzysztof Kieslowski named it as one of his favorite films.
A digitally restored version of the film was released on DVD and Blu-ray by The Criterion Collection in April 2011. The extras feature a new documentary featuring Loach, Menges, producer Tony Garnett, and actor David Bradley, a 1993 episode of The South Bank Show with Ken Loach, Cathy Come Home (1966), an early television feature by Loach, with an afterword by film writer Graham Fuller, and an alternate, internationally released soundtrack, with postsync dialogue.1970: Karlovy Vary International Film Festival – Crystal Globe
1971: Writers' Guild of Great Britain Award – Best British Screenplay
1971: British Academy Film Awards
Best Actor in a Supporting Role – Colin Welland
Most Promising Newcomer to Leading Film Roles – David Bradley
Golding, Simon W. (2006). Life After Kes: The Making of the British Film Classic, the People, the Story and Its Legacy. Shropshire, UK: GET Publishing. ISBN 0-9548793-3-3.
Till, L. & Hines, B. (2000). Kes: Play, London: Nick Hern Books. ISBN 978-1-85459-486-0