Hi,
Alfred Black was born 1st quarter of 1906, not 1905, see the GRO reference I posted, above - that came direct from the Record Office web facility:
https://www.gro.gov.uk/gro/content/certificates/indexes_search.aspI don't have any further info on their descendants, as it's Mary Ann's sister, Lillie who is my direct ancestor. She married George Smith in 1899 and had six kids. On the 1911 census it is noted that "wife is away" and I have found no further trace of her.
Back to Black, I have just done a quick search and found the following:
The marriage of Alfred to Constance in Loughborough in 1929:
https://familysearch.org/ark:/61903/1:1:QV89-8T3SA decade later, there is a marriage of an Alfred Black to Ida M Jukes, also in Loughborough:
https://familysearch.org/ark:/61903/1:1:QV8V-B2YMFrances A Black (Alfred and Mary Ann's daughter) married Frederick W Pateman in 1930:
https://familysearch.org/ark:/61903/1:1:QV8S-7HJ5Mary Ann Black's death:
https://familysearch.org/ark:/61903/1:1:QVH9-SK75Mary Ann Cullen's father was William James Cullen (b 1847, Canterbury, Kent, d 1922 Loughboro') and her mother was Elizabeth Hoverd (born1854 in Newcastle on Tyne, d 1931, Loughboro') who married in Kendal, Westmorland in 1872. They had 14 kids in many different places including Scotland, Durham, Liverpool, Westmorland, Barrow in Furness, Worcestershire, Essex, Yorkshire and Northampton. He was a worker on railway construction, hence why they got around a lot.
I also found the three Black children you mentioned, born 1931, 1934 and 1937. No others with the mother's maiden name of Holmes came to light in my searches. This would fit with the parents divorcing and their father possibly re-marrying in 1939, to Ida M Jukes. I found one child named Black with mother Jukes, born in Loughborough in 1945.
The only Ida M Jukes I can find was born Chesterfield 1913, MMN Chambers.
https://familysearch.org/ark:/61903/1:1:2FPT-4PR