Hmm ... I don't think I'm any further forward!
The 4Q 1874 death certificate shows:
Thomas Henry Butler, 23 years, Barman, Abcess in kidney 4 weeks ... and the informant is E.M. Butler of Cheshunt, present at death
This compares with the Thomas Henry Butler in the 1871 census:
Thomas H Butler, age 20, Shipping Clerk, in Pancras Parish/District
The mother in 1871 is Elizabeth A. Could be mis-recorded as "E.M" on the death certificate - but then "E.M." could be father, brother, wife, anything, so that's a real stretch.
On the other hand, I cannot find any Thomas H. Butler (born 1851) or E.M. Butler (sex and birthdate unknown) in Cheshunt or vicinity in the 1871 census.
Any suggestions?