William E JAMES/NANCE was 43 yrs. and a coal merchant born Padstow, Cornwall.
This is the only entry for the name Nance in 1861 (Glamorganshire):
Glamorgan Family History Society 1861 Census CD
4036 1861 CENSUS OF CARDIFF ST.MARY. REF.R.G.9/4036, E.D.17.
Piece: 4036 Folio: 098 Schedule: 128
Address: MOUNT STUART SQ 12
TROUNCE WILLIAM HD M 41 SHIPBROKER
CON BREAGE (c1820)
TROUNCE MARY WI M 38 -
CON PENZANCE (c1823)
TROUNCE WILLIAM SO U 18 -
CON PENZANCE (c1843)
TROUNCE MARIE DA U 16 -
CON PENZANCE (c1845)
TROUNCE HENRY SO U 9 SCHOLAR
GLA CARDIFF (c1852)
TROUNCE THOMAS SO U 7 SCHOLAR
GLA CARDIFF (c1854)
TROUNCE SUSAN DA U 6 SCHOLAR
GLA CARDIFF (c1855)
NANCE WILLIAM BO U 23 COAL MERCHANTS CLERK
CON PADSTOW (c1838)
If you are interested I found this entry within the 1851 census for Glamorgan (These 3 are the only individuals listed in Glamorgan with that surname):
2455 1851 CENSUS OF CARDIFF (NORTH-EAST). REF.H.O.107/2455, E.D.4B.
Piece: 2455 Folio: 120 Schedule: 159
Address: 5 WELLINGTON TERRACE
NANCE WILLIAM HD M 34 SHIP BROKER
CON PADSTOW (c1817)
NANCE SIBYL E. WI M 33 -
GLA CARDIFF (c1818)
NANCE EMILY DA - 7 -
GLA CARDIFF (c1844)
DAVIES JANE SV U 17 HOUSE SERVANT
GLA PENTYRCH (c1834)
Henry was at 14 Stacey Rd., Roath., Glamorgan in 1881 and was a widower by 1881. This might be the more likely location as the others had children under 10 yrs. old.
You mention a Henry (not sure of dates for him) but here is an 1841 Glamorgan entry for the name:
Glamorgan Family History Society 1841 Census CD
District Name: Swansea Enumeration District: 3 Clase (Morriston)
Piece: 1419/01 Folio: 057 Schedule: 112A
Address: MORRISTON PB & MB
S 18 057 112A MORRISTON PB & MB EDWARD JOSEPH 5 (c1836)
- YES
S 18 NANCE HENRY 26 (c1815)
SINKER NO
(Yes = Born in Glamorgan , No = Not born in Glamorgan)