Her parents married in 1948; Carmella Brett and Leslie Riddell. Her grandfather was John George Riddell, who looked after Grimsby fish market, and died in May 1949. Riddell was born in
Grimsby, at Nunsthorpe Maternity Home, and first lived at 147 Scartho Road. She attended
Boston High School, a girls'
grammar school. In March 1965, she took part in a production of 'Blue Murder' by Kenneth Lillington, and as Arabella in Three Blind Mice by Cuthbert Taylor. She represented Holland in county cross country competitions in 1970. In 1970 she took part in the Lincolnshire Youth Theatre. She gained English, French and German A-levels in 1970. She studied Modern Languages at the
University of Nottingham. She grew up in a Catholic family with sisters Sheila and Maddi and brother John. Her sister is Professor
Sheila Riddell (born 2 December 1953), an academic at the
University of Edinburgh and Director of the Centre for Research in Education Inclusion and Diversity (CREID), who is married to Professor Ken Sorbie, Professor of Petroleum Engineering at
Heriot-Watt University since 1992. ==Career==