Local accent can affect indexing, so search on variants.

Especially in British records: don't forget to search on variant pronunciations per local accent. An /r/ can affect indexing, so try with and without; in earlier baptisms, the surname Dagg is given as Darg(ue), so including an /r/ may be necessary to push back further. In one census, Boldon is recorded as Bowden (or something similar; I'd have to look it up again). In Philadelphia records, Boeger is given as Berger, Böger, Bager, Bohager.