Ruth suffered from asthma and was sent to live for four years with her Streatfeild grandparents where she was looked after by a nurse, rather than stay in the damp Amberley Vicarage.
After the war Gervis continued teaching and exhibited widely and then took over the studio and pupils of her original teacher, Miss McMunn.
She married Shorland Gervis (known as Shor) who a science master at the Boys' School in Sherborne, where they lived together at Nortons, The Avenue.
Ruth became more widely known as a successful illustrator of children's books such as those by Paula Harris, Mary Treadgold, Kitty Barne and the Caravan Family series by Enid Blyton.
After her husband Shor died in 1968, Gervis became a founder member of the Museum at Sherborne, participating on its Council and taking a supporting role for twenty years.