There is a death notice in the Liverpool Echo on 3rd Jan 1972 for a Mary Hart who died on 31st Dec 1971 who was to be buried at Yew Tree (not Ford) which may save Marienne from searching for her in Ford. If this sounds like your Mary Hart that is :-)
As we are not allowed to post about living people I have just given the initials of her children mentioned.
HART December 31 1971, in hospital aged 75. MARY HART dearly loved wife of the late Edward and dear mother of M*, E*, P*, J*, E*, M*, K*, L* and also Elizabeth and John (deceased) dear mother in law of her Sons in law and Daughters in law and loving nin of her grandchildren and Great Grandchildren (R.I.P.) Requiem Mass at St Patrick’s Church on Friday next at 9a.m. interment following at Yew Tree Cemetery
—5 Grey St Liverpool 8
Boo