Charles appeared as an actress in repertory theatre in her twenties, but initially had difficulty obtaining Equity membership due to her resemblance to the Queen. She has since played the role in numerous films including Secrets of a Superstud (1976), Queen Kong (1976), The Rutles' movie All You Need Is Cash (1978), National Lampoon's European Vacation (1985), The Naked Gun: From the Files of Police Squad! (1988) and Austin Powers in Goldmember (2002).

She also appeared as a semi-regular in Spike Milligan's Q series on BBC Television and appeared on Channel 4's Big Brother 10 to surprise the Brazilian contestant Rodrigo Lopes (who thought he was meeting the real Queen Elizabeth II for a task).

She also appeared in Saturday Night Live episode, Season 2, Episode 20 in 1977 and Mind Your Language episode, Season 2 Episode 2 Queen For a Day in 1978.

She retired in 2014 and resides in Chelmsford, Essex.