John Allen's age wobbles about all over the show (as does wife Sarah's), but he's pretty consistent with occupation as a Fitter, Iron works - though in 1895 described as a Hostler.
1861: 23 Hall St, Aberdare, Glam. Age 32, married ( to Margaret nee Wigley) Fitter, b Blaby, Leicestershire.
1871: 4 Waterloo Place, Aberdare, Glam. Age 45, widower, Fitter, b Blaby, Leicestershire.
1881: 7 Saxon St, Llantwit Fardre, Pontypridd, age 47, Fitter, Park Iron Works, b Town, Leicestershire. Sarah Ann is 37, b Brynamman, Carmarthenshire
1890: 23 Wine St Pontlottyn, Gelligaer, Fitter (baptism son Oliver)
1891: 23 Wine St, Pontlottyn, Gelligaer, age 60, ½ time Labourer Iron Works b Leicester, Leicestershire. Sarah 44, b Brynmawr, Breconshire
1895: 23 Wine St, Pontlottyn, Hostler ( baptism of son Charles) Wesley)
1901: 21 Wine St, age 76,( no occupation) b Blaby, Leicestershire. Sarah A is 50, b Brynmawr, Brecknock
I suppose he could have been a Special Constable? But given Sydney's notable conversion of his age and DoB, and alternative PoB - one wonders...
Interestingly, the same ALLEN family pop up in this 2020 post!
https://www.rootschat.com/forum/index.php?topic=834059.9Cheers,
AMBLY