In 2008, Castle was named by "The Guardian" as one of four of "Labour's greatest heroes" and in 2016 she was named on BBC Radio 4's "Woman's Hour" Power List as one of seven women judged to have had the biggest impact on women's lives over the past 70 years, alongside Margaret Thatcher, Helen Brook, Germaine Greer, Jayaben Desai, Bridget Jones, and Beyoncé. Several women politicians have cited Castle as an inspiration for embarking on their careers, including Shadow Foreign Secretary Emily Thornberry, Tulip Siddiq, and former Conservative MP Edwina Currie.