She served for more than three decades with the Citizens Advice Bureau and made significant contributions to work on drug misuse, for which she was awarded the OBE in 1991, which was later elevated to DBE.
Ruth Runciman was an early trustee of the National AIDS Trust (now known as NAT), and served as its Chair from 2000 to 2006. She was a founder of the Prison Reform Trust in 1981. She was responsible for setting up a full-time Citizens' Advice Bureau in Wormwood Scrubs, the first full-time independent advice agency in any prison. She was also a Trustee of the Pilgrim Trust. The University of Central Lancashire conferred an Honorary Fellowship on Dame Ruth Runciman at an Awards Ceremony in 2000.
She was Chair of Central and North West London NHS Foundation Trust for more than ten years, retiring at the end of 2013.
Between 1959 and 1962 she was married to Denis Mack Smith, a noted historian of the Italian "Risorgimento". In 1963 she became the wife of British sociologist Garry Runciman: as such she can be styled as Viscountess Runciman of Doxford, a title she does not use. Her son David is a Professor of Politics and a fellow of Trinity Hall, Cambridge.
- Runciman of Doxford, Viscountess; Ruth Runciman. Who's Who. A & C Black. 2001. p. 1809.
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- "Truestees' Report and Accounts" (PDF). The Pilgrim Trust.
- "Honorary Fellows 1992-2009 Fellows". The University of Central Lancashire.
- "New chair for NHS Foundation Trust who will overlook centres in Milton Keynes". MK Web. 11 January 2014. Retrieved 11 January 2014.
- "David Runciman". Department of Politics and International Studies (POLIS), University of Cambridge. Retrieved 10 April 2018.