Collins didn't become an international star until 1970, when she appeared as the charming, saucy maid Sarah in the first season of London Weekend Television's classic "Upstairs Downstairs" (debuting in the US on PBS in 1974). Her ability to switch from boisterous comedy to stark tragedy made her the hit of the series. Collins' husband (since 1969), John Alderton, appeared on that show, and the two were also featured on such British series as "Thomas and Sarah" (an ill- advised "Upstairs Downstairs" spin-off), "Forever Green", the popular "No--Honestly" and the amusingly fey "Wodehouse Playhouse". Sans Alderton, Collins was seen in "Country Matters" (shown on PBS in 1979) and "The Black Tower" (shown on PBS in 1988).
The second blossoming of Collins' career came in 1988 with a starring role in "Shirley Valentine", a one-woman show about a discontented, middle-aged housewife. Winning a Laurence Olivier Award, Collins brought the show to Broadway, where she won several more awards (including a Tony) in 1989. She reprised the role later that same year in the feature version of "Shirley Valentine", which had been expanded from its monologue format. She followed with a co- starring role opposite Patrick Swayze in Roland Jaffe's "City of Joy" (1992) as the operator of a dispensary in Calcutta, India. Collins ventured to Germany to film "My Mother's Courage" (1995, released in the USA in 1997), a concentration camp drama in which she protrayed writer George Tabori's mother. More recently, she was one of the European women detained in a prison camp in Malaysia in Bruce Beresford's "Paradise Road" (1997).