DoB from death aged 70 in 1878.

May have died by 1862 when the name James Gibson seems to have vanished from the Griffiths Valuation Revision Book.

1878    Gibson    James    70    1808    Coleraine    1;348 4Q    BG    ORDER THIS ONE - must be my GGG GF (only Coleraine Gibson in 10 years)    Derry FHC

Death Certificate from Roscommon:
23rd December 1878, Letterloan; James Gibson; Male; Married; 70 years; Labourer; Bronchitis two weeks certified; Ellen McKeown, her mark, PAD, Letterloan.

DoB from death aged 76 in 1888.

1888    Gibson    Jane    76    1812    Coleraine    1;364 2Q    BB    ORDER THIS ONE - must be my GGG GM    Derry FHC

Death Cert from Roscommon:
1st June 1888, Balteagh; Jane Gibson; Female; Widow; 76 years; Widow of weaver; Debility 4 years. uncertified, no med attend; Sarah Doey, her mark, daughter, Present at Death, Letterloan.

Date of Birth Source = Old Age Pension Search results for Nancy Gibson.  In the 1901 census, if this is the same William, he gives his age as 70 = Date of Birth of 1831.

Date of Birth and Date of Death Sources: Old Age Pension Search results for Nancy Gibson.

Date of Death and Date of Death Sources: Old Age Pension Search results for Nancy Gibson.

Date of Birth and Date of Death Sources: Old Age Pension Search results for Nancy Gibson.

Date of Death and Date of Death Sources: Old Age Pension Search results for Nancy Gibson.

Date of Birth Source = Old Age Pension Search results for Nancy Gibson.  

May be dead when his name disappears from the Griffiths Valuation Revision Book in 1885 and a Jane appears in a different house but seems unlikely.

Date of Birth source: Old Age Pension Search results for Nancy Gibson.  1901 census gives her as 58 = 1843.  

She was informant at husband's death so lived beyond 1902.

This might be her:
Residents of a house 1 in Blagh (Ballylagan, Londonderry)
Surname    Forename    Age    Sex    Relation to head    Religion    Birthplace    Occupation    Literacy    Irish Language    Marital Status    Specified Illnesses    Years Married    Children Born    Children Living
Mc Curley    Mary Ann    51    Female    Head of Family    Church of Ireland    Co Londonderry    -    Read and write    -    Widow    -    29    6    5
Mc Curley    Ellen    19    Female    Daughter    Church of Ireland    Co Antrim    Shirt Maker    Read and write    -    Single    -    -    -    -
Mc Curley    Edward    13    Male    Son    Church of Ireland    Co Antrim    Scholar    Read and write    -    Single    -    -    -    -
Mc Keown    Eliza Ann    72    Female    Visitor    Presbyterian    Co Londonderry    -    Read only    -    Widow    -    -    -    


1914    McKeown    Ellen    70    1844    Coleraine    1;353    BG    
ORDER THIS ONE!  Probably my great great grandmother, Ellen Gibson - only Ellen in CRs    LDS Pilot
Coleraine Union, Coleraine; 23 April 1914, Infirmary, Coleraine; Ellen McKeown of Macosquin; Female; Widow; 70 years; House Keeper; Cerebral Haemorrhage. Two years, Cardiac Debility, Certified; Martha J Coleman, Occupier, Matron, Workhouse, Coleraine.
BG:  I think this means that she was in the hospital in Coleraine not the workhouse and that the registry office was in the workhouse.  In fact, Coleraine hospital WAS in the old workhouse.

Date of Birth = Nancy claiming to be 70 at time of her Old Age Pension Census Enquiry.  Not in 1851 census when OAP search done, so no definite Date of Birth, and 1839 would make her a twin of my Ellen, which seems unlikely.

Date of Birth Source: Old Age Pension Search results for Nancy Gibson.

Date of Birth Source: Old Age Pension Search results for Nancy Gibson.

Not in 1851 census when Old Age Pension search done for her sister, Nancy, so no Date of Birth.