|Directed by||Lewis Gilbert|
|Produced by||Daniel M. Angel|
|Screenplay by||Lewis Gilbert
|Based on||play Master Crook by Bruce Walker|
|Music by||Lambert Williamson|
|Edited by||Charles Hasse|
|Box office||£112,918 (UK)|
Cosh Boy (released in the United States as The Slasher) is a 1953 British film noir directed by Lewis Gilbert and starring James Kenney and Joan Collins. It was made at the Riverside Studios in Hammersmith.
Poster taglines: "The burning question of to-day! Are they getting the punishment they deserve? - These bandits of society!" 
The gang starts off by mugging women. Later, Roy becomes infatuated with Rene, the sister of one of the gang members. Already having a boyfriend, Brian, she rejects Roy, to his fury. Later the gang beat up Brian. Roy menaces Rene, who eventually submits to him. When she informs him that he has made her pregnant, and urges him to marry her, he decides he wants nothing more to do with her.
Roy's mother, Elsie Walsh (Betty Ann Davies), is involved with Canadian Bob Stevens (Robert Ayres), who urges her to marry him so he can take Roy "in hand" before it's too late. Roy hates Bob.
Bob works as an assistant manager at the Palidrome dance hall, which becomes a target for the gang. Another member of staff appears on the scene, and is shot and wounded by the gang.
Later that night a mob of women arrive on the doorstep with Rene's mother, who adds that the police are on their way. Bob arrives, removes Rene's mother from the premises and decides to give Roy a thrashing - for his own good - before the police arrive in the belief that if the judge hears he has already received a thrashing, his sentence might be lighter, which will be easier for his mother to stomach. The police arrive just as Bob is brandishing his belt in readiness. Bob lets them in, and they ask who he is. He tells him he is the boy's stepfather, as "his mother and I were married this morning".
The leading officer congratulates him, then, seeing the belt in his hand, smiles, and suggests to his colleague that they go and arrest the other gang member first and come back for Roy later. Bob begins thrashing Roy as the scene cuts to outside and the mob of women listening to Roy's cries and shrieks for help. The detectives then walk away, into the night.
- James Kenney as Roy Walsh
- Joan Collins as Rene Collins
- Betty Ann Davies as Elsie Walsh
- Robert Ayres as Bob Stevens
- Hermione Baddeley as Mrs. Collins
- Hermione Gingold as Queenie
- Nancy Roberts as Gran Walsh
- Laurence Naismith as Inspector Donaldson
- Ian Whittaker as Alfie Collins
- Stanley Escane as Pete
- Michael McKeag as Brian
- Sean Lynch as Darky
- Johnny Briggs as Skinny Johnson
- Edward Evans as Sergeant Woods
- Cameron Hall as Mr. Beverley
- Sid James as Police Sergeant
Cosh Boy has also been named The Tough Guy, or The Slasher. It was among the first British films to receive the new X certificate. It was given a Certificate rating of 16 in Norway (1953), and banned in Sweden.
- Vincent Porter, 'The Robert Clark Account', Historical Journal of Film, Radio and Television, Vol 20 No 4, 2000 p499
- "Dix’s Cult Classics : Cosh Boy (1953) - Six Impossible Things Before Breakfast". Six Impossible Things Before Breakfast.