Re: background/family history of Catherine Johns of Tintagel
I've managed to do a bit of research for you now. Catherine Eliza Johns was aged 60 in 1901 and was living nr St Nectans Glen with a single servant. She was living on her own means and was born at Minster on the Isle of Sheppey, Kent. So perhaps not Cornish after all. Here are some details from the Census information in the UK for most of her life up to age 60:
Aged ten she was living in Plymouth at Durnford Street, Devonport, with the following other people:
Louisa Johns Female 43 born London
Louisa C. Johns Female 21 born Portsmouth
Richard Johns Male 19 born Plymouth
Tremenheere Johns Male 12 born Kent
Vyvyan Johns Male 4 born Kent
Caroline Laugharne Female 26 born Newfoundland
Louisa Northcote Female 27 born St Teath.
Unfortunately I can't identify all their relationships to Catherine but it looks like her mother, brothers and servants at least.
In 1861 Catherine (Eliza) Johns was living with her mother "Louisa Percival Johns" noted as the head of the family, (born in Newington, London), her mother's unmarried brother "Erasmus Mason" who was the curate of the village, and a servant at "Sunny Lands", Dalwood, Axminster, Devon.
In 1871 age 30 she was living with other her 24 year old brother and an aunt by marriage (listed as a lodger) who was a naval pensioner of sorts, at 2 Wilby Road, Camberwell, London. Catherine herself is noted as single and with no occupation.
1891 saw the single, 40 year old Catherine living at 174 Osborne Road, Windsor, Berkshire again with her widowed mother, now 86. They are both listed as living on their own means and the household has two servants living in.
So, I haven't yet identified her as an artist nor the name of her father but I suspect the family was a naval or military family whose father was always away.
The "Gift House" used to be the stable belonging to the "Old Post Office" in Tintagel until it was re-built.
I hope some of this helps, it may well be that you are not related to this Catherine Johns, however, if you have any other clues to your ancestry please let me know and I'll see what I can find for you.