She is known for her roles in films The Servant (1963), Blowup (1966), Ryan's Daughter (1970), The Man Who Loved Cat Dancing (1973), White Mischief (1987) and Hope and Glory (1987).

[6] Shortly after finishing at RADA, Miles performed in an episode of the TV series Deadline Midnight titled "Manhunt".

Her film debut was as Shirley Taylor, a "husky wide-eyed nymphet"[7] in Term of Trial (1962), which featured Laurence Olivier; she was nominated for the BAFTA Award for Best Newcomer.

Miles appeared in The Rehearsal (1963) for TV and then played Vera from Manchester in Joseph Losey's The Servant (1963), and "thrust sexual appetite into British films" according to David Thomson.

16 June 1965 saw the release of Ken Annakin's Those Magnificent Men in Their Flying Machines, a British period comedy film revolving around the craze of early aviation circa 1910.

A pompous newspaper magnate (Robert Morley) is convinced, by his daughter (Miles) and her fiancé (James Fox), to organise an air race from London to Paris.

The film received positive reviews, described as funny, colourful and clever, capturing the early enthusiasm for aviation.

[11] After acting in several plays from 1966 to 1969, Miles was cast as Rosy in the leading title role of David Lean's Ryan's Daughter (1970).

On 11 February 1973, while filming The Man Who Loved Cat Dancing, aspiring screenwriter David Whiting, who was briefly one of her lovers,[14] was found dead in her motel room.

Miles appeared in The Big Sleep (1978), Venom (1981), Walter and June (1983), Ordeal by Innocence (1984), Steaming (1985), Harem (1986) and Queenie (1987).

Interviewer Lynn Barber wrote of Miles' appearances in Hope and Glory, White Mischief, and her two earliest films that she "has that Vanessa Redgrave quality of seeming to have one skin fewer than normal people, so that the emotion comes over unmuffled and bare.

"[5] Filming White Mischief on location in Kenya in 1987, Miles worked for the second and last time with Trevor Howard, who had a supporting role, but was by then seriously ill from alcoholism.

In an interview with Terence Pettigrew for his biography of Howard, she describes how she gave an ultimatum to the executives, threatening to quit the production if they got rid of him.