Here's my Irish brickwall. Well - one of them...
Daniel Cullen lived in Glasgow most of his life but was from Ireland.
Known to be him:
MARRIAGE
Glasgow, St Vincent Chapel (Catholic)
1872 Jul 15
to Jane McMullen (elsewhere McMullan/McMillan)
Age: 20
Parents: Michael Cullen, farmer. Susanna McGeogh, deceased.
Jane died 1874.
MARRIAGE
Glasgow, St Andrew's Chapel (Catholic)
1876 Apr 24
to Elizabeth Blaney
Age: 24
Parents: Michael Cullen, farmer. Susanna McGeoch, deceased.
CENSUSES: Consistently living in Glasgow, born in Ireland, carter/driver.
1881 age27
1891 age39
1901 age47
1911 age59
DEATH
Glasgow
1916 Apr 06
Age: 65
Parents: Michael Cullen, labourer, deceased. Catherine McKeogh, deceased.
Potentially him:
CENSUS 1871
Glasgow, Bridgeton, 254 Dalmarnock Road
Age 20
Lodger. Carter.
Possible BIRTH:
Co Armagh, Ballymore and Mullabrack parish (Catholic) - parish registers
1849 Jul 16
Parents: Mi..l Cullen, Susanna McGeough
I don't know how common these names are (i.e. is it a coincidence) and his birthdate in known documents as above varies from 1850 to 1854 - average around 1852 - so this is a bit early.
If it IS him - well, I can't find any more about the family in Ireland, and would love to.
Miscellaneous:
No evidence found of his parents/siblings in Scotland.
Both his wives were also Irish; Jane lived with her mother and siblings in Glasgow.
Any tips? Let me know if you need more detail on the evidence above.