Joanna read English and History at the University of York. She subsequently received British Academy funding for an MA on Women in the Late Medieval World and for a DPhil on queenship during the Wars of the Roses at the University of York's Centre for Medieval Studies. Her DPhil thesis was published by OUP as The Last Medieval Queens in 2004 and it jointly won both the Longman-History Today Book of the Year Prize and the Women's History Network Book Prize.
She taught medieval history at Pembroke College, Oxford for two years shortly after her marriage and then returned to Yorkshire where she taught briefly at the Universities of York and Huddersfield before the birth of her first son. She stopped teaching to be a full time mother but continued writing, publishing articles, and giving occasional talks and conference papers. She is now a Visiting Research Fellow at the University of Reading's Graduate Centre for Medieval Studies and was elected a Fellow of the Royal Historical Society in 2018.
She presents talks on medieval queens and the women in Richard III's family, usually to local history groups, Richard III Society branches and schools. She has appeared in documentaries, including BBC2's, The Real White Queen and her Rivals (2013) and History Hit's Richard III Brutal Medieval Tyrant or Misunderstood? (2024) as well as In Our Time: Margaret of Anjou (24 May 2018) and various podcasts. She has taught a number of courses on The Wars of the Roses and on Medieval Women for the WEA. She was the Research Officer for the Richard III Society until 2022 and still regularly contributes articles to their Bulletin.
In 2017 she published a biography of Cecily Duchess of York with Bloomsbury Academic and this won the 2018 Royal Studies Network Book Prize. Her recent academic work includes a volume co-edited with Ellie Woodacre: Later Plantagenet and the Wars of the Roses Consorts and articles on demythologising Edith Swanneck, queens and the royal family in later Medieval England, and the Princes in the Tower.
Her principal research project at present is a study of the politics of royal adultery in Britain 500-1140 and she is now the editor of The Ricardian (the academic journal of the Richard III Society). She is also a trustee of the Yorkist History Trust.