How many television series did the sitcom in which Liz Smith played the role of a character called "Nana" run for?
Liz Smith (actress): Betty Gleadle, {'1': ", '2': ", '3': ", '4': "} (11 December 1921 – 24 December 2016), known by the stage name Liz Smith, was an English character actress, known for her roles in BBC sitcoms, including as Annie Brandon in "I Didn't Know You Cared" (1975–79), Bette and Aunt Belle in "2point4 Children" (1991–99), Letitia Cropley in "The Vicar of Dibley" (1994–96), and Norma Speakman ("Nana") in "The Royle Family" (1998–2006). The Royle Family: The Royle Family is a British television sitcom produced by ITV Studios for the BBC, which ran for three series from 1998-2000, and specials from 2006-12.
three