Hi John - to add to Tom's info here are the certificate details for your mum's marriage and death, there may be more clues to her origin or other relatives there. I've checked the appropriate births in the England & Wales BMD and also the 1911 census but unfortuantely its inconclusive - there was a "Grace Ferrol" born in 1900 in West Derby, Lancashire AND ALSO a "Grace Farrell" born in Q1, 1902 in Holborn, London but whether one of these is your mother is not certain.
MARRIAGE
Bride: FARRELL, Grace M
Groom: HIGGINSON, Douglas A
Registration district: West Derby
County: Lancashire
Year of registration: 1928
Quarter of registration: Jul-Aug-Sep
Volume no: 8B
Page no: 1057
DEATH
Name: HIGGINSON, Grace M
Registration district: Liverpool South
County: Lancashire
Year of registration: 1943
Quarter of registration: Jan-Feb-Mar
Age at death:42
Volume no: 8B
Page no: 55
Cheers