Margaret John
From Tardis Wiki, the free Doctor Who reference
Margaret John (14 December 1926-2 February 2011[1][2]) appeared in two Doctor Who television stories: as Megan Jones in Fury from the Deep and Grandma Connolly in Tardisode 7 and The Idiot's Lantern.
John held the record of the longest gap — 38 years — between Doctor Who appearances until Ysanne Churchman returned to the show in 2017 after a 43 year gap.
Her television career spanned over five decades, from Bronwen in a 1960 BBC production of How Green Was My Valley to Old Nan in the first season of HBO's Game of Thrones, which aired after her death in 2011.
