Hello Liz, now don't get your hopes up, but this could be worth checking,

first, you need to check the 1891 and 1901 Census for the following John Cain,

and then check for his burial date and WILLs to see if MAYBE the son Robert inherited the CARTER business,

Occupation = CARTER

I found on the 1881 census,

Dwelling 11 Osborne Grove
Census Place Douglas, Isle of Man,
Family History Library Film 1342347
Public Records Office Reference RG11
Piece / Folio 5605 / 68
Page Number 16

John CAINE Head M Male 55 Michael, Isle of Man, England Carter
Anne Jane CAINE Daur U Female 20 Michael, Isle of Man, England Dressmaker
Catherine C. CAINE Daur U Female 16 Michael, Isle of Man, England Home Servant
Frederick T. CAINE Son Male 14 Patrick, Isle of Man, England Scholar
Robert E. CAINE Son Male 12 Patrick, Isle of Man, England Scholar
Alice CAINE Daur Female 10 Patrick, Isle of Man, England Scholar
Robert HARDY Lodger M Male 58 Ireland Military Pensioner

WILLs
CAIN, John 1883 Bra
CAIN, John 1887 Dgs
CAINE, John 1889 Dgs
CAINE, John 1891 Ram
CAINE, John 1892 Dgs
CAIN, John 1894 Dgs
CAIN, John Thomas 1895 Onc

ANN JANE CAINE
Christening: 25 OCT 1860 Kirk Michael, Isle Of Man, England
Parents:
Father: JOHN CAINE Family
Mother: ELIZABETH

CATHARINE CHRISTIAN CAINE
Christening: 15 JAN 1865 Kirk Michael, Isle Of Man, England
Parents:
Father: JOHN CAINE Family
Mother: ELIZABETH

FREDERIC THOMAS CAINE
Christening: 13 JAN 1867 Patrick, Isle Of Man, England
Parents:
Father: JOHN CAINE
Mother: ELIZABETH

ROBERT EDWIN CAIN
Christening: 31 JUL 1869 Patrick, Isle Of Man, England
Parents:
Father: JOHN CAIN Family
Mother: ELIZABETH

ALICE CAIN
Christening: 19 MAR 1871 Patrick, Isle Of Man, England
Parents:
Father: JOHN CAIN Family
Mother: ELIZABETH

and I do hope this helps,
Averil