The very first problem I see with this one is that the birthdate does not match the age in the Census record!
To be age 4 in 1891 I would suggest Janie was born in 1886 or possibly 1887 which is at least two years prior to the date recorded in Susie's Birthday Book.
I checked through the Census and in 1901 you will find Jane and daughter Janie, now age 14, still living at Ludgvan. Also present is another daughter - Minnie age 6.
In 1911 I finally found the father at home!
1911 Census
4 Church Street, Helston
Richard Henry CURNOW, age 54, Inn Keeper, born Ludgvan
Jane do., wife, age 53, assisting in the business, born Ludgvan
Jane do., daughter, age 24, assisting in the business, born Ludgvan
John PERRY, boarder, age 56, married, farmer, born Wendron
Minnie CURNOW, daughter, age 17, assisting in the business, born Ludgvan
13th March 1886 Ludgvan - by Banns
Richard Henry Curnow, 29, bachelor, miner of Ludgvan, son of Thomas Curnow, miner
Jane Roberts, 28, spinster of Ludgvan, daughter of William Roberts, miner
Witnesses - Richard Roberts, Elizabeth Jenkin
There appears to be no other Jane/Janie Curnow in the Census who might be the girl in Susie's book which leads me to suspect that she was not born in the UK.
Interesting!
- Assuming the birthdate of August 3rd, 1889 is accurately recorded then the birth should have been registered in the September Qtr of that year.
I just checked FreeBMD and there are but five Curnow births registered in the UK in that particular quarter and of those there are two females - Honor Elizabeth and Sophia Ann.
I then checked the whole year and there is not one birth registered in 1889 where Jane/Janie forms any part of the name.
If born in England then the only other possibility might be that Janie was a particular friend of Susie and that Curnow was her married name.
But even if that were the case she still does not appear in the Census which again suggests she was not in England even if she had been born there.
CT