Hi Lesley
I just put Charlotte (no surname), age 32 b.IoM, residence IoM, into the 1961 census on findmypast.com - it came up with 4 Charlottes, one of whom has surname Conlly; also under Conlly are all the rest of the Cowley family. I can see how they could mistake the surname, but it is clearly "Cowley" . findmypast.com obviously didn't use local expertise when transcribing the census onto their database.
JohnL