The time of baptism should not have affected when a birth was registered - which is supposed to be done within 42 days of the birth.
FreeBMD:
http://www.freebmd.org.uk/cgi/search.pl shows a Thomas Cornelius Ward birth registered in Cheltenham district in December quarter of 1865.
The 1871 census shows a likely Ward family living at 38 Queen Street in Cheltenham:
Cornelius Ward head M 40 Labourer
Sarah Ward wife M 39
Elizabeth Ward daur 12
William Ward son 11
Sarah A Ward daur 9
Mary Ward daur 7
Thomas Ward son 5
Ellen Ward daur 1
(census ref Class: RG10/ Piece: 2668/ Folio: 24/ Page: 8 )
The whole family are recorded as born in Cheltenham, but Cornelius Ward, living with his widowed mother in 1851, has his birthplace down as Forest of Dean (he is the only Cornelius Ward born in Gloucestershire showing in 1851):
51, Stanhope Street, Cheltenham
Sophia Ward head W 60 supported by the parish Wiltshire, Malmesbury
Cornelius Ward son U 21 Agricultural lab. Gloucs, Forest of Dean
Priscilla Ward daur U 18 Gloucs, Cheltenham
Caroline Stacey Gdaur U17 Gloucs, Cheltenham
(census ref Class: HO107/ Piece: 1973/ Folio: 502/ Page: 24)
The International Genealogical Index (IGI) on
http://www.familysearch.org/Eng/Search/frameset_search.aspshows a baptism of Cornelius Ward son of William and Sophia at Blakeney in 1828. If it is the same Cornelius he must have been about seven or eight years old - which does lend support to the story about waiting for the bishop.
However this is the only child of William and Sophia Ward baptised at Blakeney showing on the IGI.
If they were waiting for the bishop you would expect a bunch of them on the same day, but in fact Cornelius appears to have been the only child baptised in Blakeney on the 25th of May 1828. (Although we have to be wary, as the IGI is not a complete record).
Some people were just a bit slow to get round to baptising their children.