This information probably isn't much help to you but Thomas Toomey is part of my family tree. He and his wife worked around Westbury on Severn as agricultural labourers for a good part of their lives and were quite poor. On at least one occasion they had a lodger paying rent to them, also caring for a farmers aged servant and doing washing to supplement their meagre income. Therefore I assume the Martins you referred to would have been boarders and not sons.
If you are interested Thomas Toomey was involved in a court case called "The Toomey Case" where he was persecuted for being an early member of an Agricultural Union. The case received extensive coverage in the Western Mail Newspaper during September 1874. One of the reports gives a good description of the families income, or lack thereof, which would have probably been typical for that occupation at the time.

Sid Toomey

I think they are in Bristol? George listed as 35 years but looks more like 55 on image.
George and Emma J both down as born in Blaisdon.

Street Morse Road
Parish Bristol
Town
City
County Gloucestershire
Country England
Ecclesiastical District St Matthew Moorfields
Enumeration District 36
Municipal Ward St George
Parliamentary Borough Bristol East
Registration District Bristol
Category Census, Land & Surveys
Record set 1901 England, Wales & Scotland Census
Collections from Great Britain

First Name Emma J
Last Name Martin
Birth Year 1845
Age 56
Birth Town Blaisdon
Birth County Gloucestershire
Birth Place England
Relationship To Head of Household Boarder
Gender Female
Occupation
Condition Married
Archive Reference RG13
Folio 106
Page 10
Piece Number 2391

First Name George
Last Name Martin
Birth Year 1866
Age 35
Birth Town Blaisdon
Birth County Gloucestershire
Birth Place England
Relationship To Head of Household Boarder
Gender Male
Occupation Miller
Condition Married
Archive Reference RG13
Folio 106
Page 10
Piece Number 2391

Regards
ChrisW