indcydd contacted me by PM for some information, but I think it's better to continue her search on here so told her I'd post what I've found so far.
I've found that Violet Smith was actually born in 1902, on 3rd April 1902 to be exact. The reason she is shown as being 8 on the 1911 census is that her 9th birthday was exactly one day after the census was taken. She was baptised on 12 October 1902 at New Ferry Parish Church, Cheshire. Her parents as incydd correctly told us were George Dennison and Mary Elizabeth Smith. George's occupation at the time was given as Book-keeper and their address was 74 Bebington Road, New Ferry. By 1911 George Dennison Smith was shown as an Audit Clerk on Chief Accountants Staff of Lever Brothers, soap manufacturers.
There are a few possible deaths but I can't find any 90+ years after Violet's birth and none which give the correct date of birth. These are all I could find:
Jan-Mar 1951 Birkenhead - a Violet Smith born about 1902
July-Sept 1976 Chester & Ellesmere Port - a Violet Smith born about 1902
July-Sept 1983 Chester & Ellesmere Port - a Violet Smith born 17.3.1902
Indcydd - What we need to know is are you sure she was in the asylum all her life? I don't know what registration district Deva Hospital, Wirral would come under. You said in your PM that you thought that would be the place she'd been sent.
If you only have this information from your dad, I wonder if he actually knew that she was in an asylum 90+ years later. If so, where did he learn that from? How do you know she died there in her 90s? Do you have more information that you can give us?
I did wonder if she had married at some time and I found a few deaths of women named Violet with a date of birth of 3.4.1902. However, when I checked out the appropriate marriages for these women, none of them had had the maiden name Smith.
My thoughts - and other Rootschatters - may have more, are that it seems a bit odd even at the time to manage to get someone into an asylum because they wanted to take up Roman Catholic religion, so I wonder a). Did she have religious mania or something, or b). Was she an unmarried pregnant girl/woman - a fact that might have been kept from her siblings.
There are quite a few births between 1917 and 1940 of babies called Smith, born to mothers whose maiden name was Smith registered in the Wirral, which is probably where they would have been registered if Violet had had an illegitimate child. There is even one named Violet C Smith born in 1920.
Lizzie