The headstone only went up last summer on her grave 'Countess Raine Spencer 1929-2016’, at North Sheen Cemetery, South-West London, five years after her death.
Prior to that there was a wooden cross.
https://images.app.goo.gl/Kdmnpr7sxb9oqqXp6
https://images.app.goo.gl/aYxtLE659yLDDW2o9
Surely Raine Countess Spencer would be more correct?