Born in Edinburgh, Scotland, Hayers began his career as a film editor. Among the films he directed are Circus of Horrors (1960), the occult thriller Night of the Eagle (1962), a musical Three Hats for Lisa (1965) and The Trap (1966).
In British TV, his credits included The Persuaders! and The New Avengers; he later directed several American TV shows, including episodes of Magnum, P.I., The A-Team, Knight Rider, T. J. Hooker, Baywatch and The Famous Five.
- Edith – original screenplay from researched notes.
- A Spy for a Spy – Screenplay adapted from the novel The Springers in collaboration with author Berkeley Mather.
- The Sweetwater Point Motel – Screenplay adapted from the novel of the same name by Peter Saab.
- The Tangled Web – Screenplay adapted fram the novel The Molester by Lee Sarokin.
- Spy Now, Pay Later – Original screenplay in collaboration with Carl Johnson and Karl-Heinz Willschrei.
- Blue Blood (TV Series) – Additional material and rewrites for seven episodes.
Feature films as director/producer
- A Night to Remember (1958) – 2nd Unit Director/Film Editor; Rank Organisation; New York Film Critics Circle – Best Ten Films; Christopher Award, N.Y.; Golden Globe Award
- Violent Moment (1959)
- Operation Amsterdam (1959) – 2nd Unit Director; Rank Organisation (Peter Finch, Eva Bartok)
- Circus of Horrors (1960) – Director; American International; Voted Horror Picture of the Year in US and UK (Anton Diffring, Erika Remberg, Donald Pleasence)
- Payroll (1961) – Director; American International (Michael Craig, Billie Whitelaw)
- Night of the Eagle (US: Burn Witch Burn, 1962) – Director; Independent Artists/Anglo Amalgamated; US Critics Prize – Best Thriller (Peter Wyngarde, Janet Blair)
- This Is My Street (1963) – Director: Rank Organisation (Ian Hendry, June Ritchie)
- Three Hats for Lisa (1965) (Musical) – Director; Fox/Rank (Sophie Hardy (French), Sid James, Joe Brown, Una Stubbs)
- The Trap (1966) – Director; Fox/Rank; 1st Prize – Czechoslovakia Film Festival; 1st Prize – Russian Film Workers Festival (Oliver Reed, Rita Tushingham)
- Finders Keepers (1966) – Director; United Artists (Cliff Richard, Robert Morley, Una Stubbs)
- Mr. Jerico (1969) (TV) – Director; Independent Artists (Patrick Macnee, Marty Allen, Connie Stevens)
- The Southern Star (1969) – Director; Columbia Pictures (George Segal, Ursula Andress, Orson Welles)
- Assault (1971) – Director; Fox/Rank (Lesley-Anne Down, Frank Finlay, Suzy Kendall)
- The Firechasers (1971) – Director; Rank Organisation (Chad Everett, Anjenette Corner)
- Revenge (1971) – Director; Fox/Rank (Joan Collins, James Booth, Kenneth Griffith)
- All Coppers Are... (1972) – Director; Fox/Rank (Ian Hendry, Martin Potter, Julia Foster)
- Deadly Strangers (1974) – Co-Producer/Director; 20th Century Fox (Simon Ward, Hayley Mills, Sterling Hayden)
- What Changed Charley Farthing? (1974) – Co-Producer/Director; Rank Organisation (Doug McClure, Hayley Mills, Lionel Jeffries)
- Diagnosis: Murder (1975) – Co-Producer/Director; Cinema International Corp. (Christopher Lee, Judy Geeson, Jon Finch)
- One Away (1976) – Co-Producer/Director; Silhouette Film Prod. (Bradford Dillman, Elke Sommer, Dean Stockwell)
- A Bridge Too Far (1977) – Director, action sequences; Joseph Levine Prod. (Michael Caine, James Caan, Sean Connery, Ryan O'Neal, Gene Hackman, Elliott Gould, Robert Redford, Laurence Olivier, Dirk Bogarde)
- The Seekers (1979) — Director; Operation Prime Time/MCA/Universal. (Randolph Mantooth, Delta Burke, Martin Milner, Brian Keith, Ross Martin)