I think I could have identified who 'Charles Kemp' was- not that it helps to identify a birth for Frances Dorothy.
As we know, Frances D. Kemp was in Plymouth in 1939 - also living in Plymouth were a Charles Kemp and wife Fanny. It's a wee bit complicated by incorrect dates/names/places being stated along the way but this is a precis of it:
Charles Kemp was born 21/4/1877 Whitstable, Kent, son of James Kemp and Eliza Holden.
(In 1875 they'd had a son Charles William Kemp, died 1876 and second son Charles registered as plain Charles - it got somewhat confusing here as there was a Charles William Kemp also born in Kent (Teyning) who had the exact same birthdate - he joined the Royal Navy but later records show he never married and died 1944 Chatham).
Anyway, plain Charles Kemp joined the Royal Marines and shown as still single in 1911!!
Then we move to Scotland - Charles Kemp, 37, Boilermans Labourer, widower(?) son of James Kemp, fisherman and Eliza nee Holden, married Fanny Holdroff 32 (? definitely not), single, dau. of Charles Holdroff, Warrant Officer, R.N. deceased and Sarah Holdroff, previously Tong, nee Sedgewood (or similar) married 7/5/1914 Pollokshields, Glasgow. Don't quite know how Charles said to be single 1911, and a widower in 1914 but definitely the same person as parents names on marriage certificate and his birthplace testify.
Fanny Holdroff is somewhat of an enigma herself when it came to give her age - she was actually born 9/2/1866 in Falmouth, Cornwall - okay whilst with family in 1871/1881/1891 but in 1901 states bc.1872, in 1911 in Devon bc.1874, 1914 bc.1882 at marriage and 1939 year is 1869. So she was actually 48 when she married Charles Kemp (so explains why they would adopt a child) but not quite sure how she got away with stating she was only 32!
Obviously, have no idea why they both left Devon (where they each were in 1911) to marry in Pollokshields, Glasgow 3 years later or how long they stayed there for. If Frances Dorothy was born 1917 then they must have stayed at least 3 years but back in Devon by 1939.
Annette