Hi Chris,
I don't have any Girling ancestors, but I do have Girling relatives. My ggggg-aunt, Sara Gifford married a William Girling in Debenham, Suffolk in 1800. There's a big gap between Suffolk 1800 and Norfolk 1878 and Girling is "locally common" in East Anglia, so no, we probably aren't related.
Norfolk has become a good place for family history - most of the parish registers have digital facsimiles on the FamilySearch site and there's a fair bit of indexing been done on FreeREG - so work your way back and see if you slide south into Suffolk. (The Norfolk family history society has also databased their transcriptions and made them available online to members.)
Good luck,
Sue