Has this person ever been mentioned?

I do not think him particularly likely, perhaps a little young (especially re age of Harry the hackney carriage driver in 1891 and age of Henry on the last census).
But having tried to find out a bit about who he was, I'll post it anyway, if we are also trying to eliminate people in the hope that we might be left with somebody who could be our Henry!
A birth in Pancras
Sep 1872 1b 61
Beale, Henry Hamblen
mother's maiden surname
— Appears to be illegitimate. Indexed as Henry Kamblen Beale on the new GRO index.
I failed to find any baptism for him.
There was another one a couple of years later, she was indexed twice by the GRO
June 1874 Pancras 1b 60
Beale, Maria Hamblen
Hamblen, Maria Hamblen
So perhaps illegitimate again, with father named? They changed the rules about that around then. Anyway, if so, we know from experience on Rootschat that the new GRO index will only have one indexing, under the father's name
June 1874 Pancras 1b 60
Hamblen, Maria Hamblen
mother's maiden surname Beale
Though I am surprised to see a mother's maiden name given.
Sadly young Maria seems to have died in Holborn district the following year.
Then there is a marriage at St Saviour, St Pancras (on ancestry)
21 April 1877
Samuel Henry Collins, 28, bachelor, Coachman
+
Maria Hamblen, 27, spinster, father William Beale, Coachman
And they are living in St George Martyr, Holborn, in 1881
Samuel Collins a Coachman, born Clerkenwell, and Maria, 31, and four children, all born Bloomsbury.
Include son Henry, 8, and there is also her mother Elmira Beale with them
https://www.familysearch.org/ark:/61903/1:1:Q279-1RTDSecond page
https://www.familysearch.org/ark:/61903/1:1:Q279-15ZFCould 8 year old Henry Collins be Henry Hamblen Beale?
There is also a 6 year old daughter Elizabeth, not sure of her birth, and she might spoil things a bit re Maria Hamblen Beale b 1874.
1891 they are in Holborn
piece 219 folio 99 page 12
Can't find them on FamilySearch
Samuel Collins is 43, a parcel post driver, Maria is 42
There are four children. No Henry with them, they have a son Alfred born since the last census.
If alive, Henry may of course be anywhere, and if under the Collins name he might be hard to find in the census.