She is best known for her role as Romana I in the BBC's science fiction television series Doctor Who,[1] appearing opposite Tom Baker in the 1978–1979 story arc The Key to Time.

[12] Tamm is best known for her role as Romana I in the BBC's science fiction television series Doctor Who,[13] appearing opposite Tom Baker in the 1978–1979 story arc The Key to Time.

[15][16] In a 2007 interview, she stated that she was willing to shoot a regeneration sequence to allow a smooth transition between her tenure and that of her eventual successor (Lalla Ward), but was not invited to do so.

[17] One source states that pregnancy was the reason that she was not asked to return, which Tamm denied as a false rumour invented by producer John Nathan-Turner.

[21] After leaving the series, Tamm took leading roles in two BBC 1 dramas, The Treachery Game (1980) and its sequel The Assassination Run (1981) alongside Malcolm Stoddard.

[22] She had a leading role in the sitcom The Hello, Goodbye Man opposite Ian Lavender in 1984 for BBC 2, around the same time as a guest appearance in Bergerac.

[18][19] Tamm had been diagnosed with cancer in 2010[28] (or "18 months" prior to her death[29]) but, as revealed by her agent Barry Langford, had kept her illness secret from all but a handful of her closest friends.