joan was far brighter than frank and, after graduating from school with 7 o-levels and an a-level, she married a chief accountant, graham (ian thompson). following their marriage, joan and graham moved to colchester, and kept little contact with joan's family in walford. after mo is diagnosed with alzheimer's disease in 1990, she starts speaking of and referring to people (mostly diane (sophie lawrence), her granddaughter) as joan, which gives some light into their relationship: mo believes that joan sees herself in a higher standing than the rest of her family, which earns mo's dislike and disapproval.