Ken, I found another Blackmore Family who are listed with the name BACKMORE (see below). The remaining family are also on the 1891 census and so I am sure that they really are Blackmore's.
The reason I found this family is that I have been searching unsuccessfully for my gg grandfather William Blackmore. Two of his children are living in Bickington (with the incorrect name Thorne, described as sister in law) with his married eldest daughter. My William (born in Burrington about 1827) had the occupation Railway Inspector on most documentation, and so I thought this was him - however his wife Ann died in 1876. I have still to find him somewhere on the 1881 census. In 1891, I found him under the name Blackmon, living in Braunton
Dwelling: Fremington Stn Census Place: Fremington, Devon, England Source: FHL Film 1341542PRO Ref RG11Piece 2251Folio 88Page 23 Marr Age Sex Birthplace William BACKMORE M 57 M Chittlehampton, Devon, England Rel: Head Occ: Railway Station Master Ann BACKMORE M 38 F Creacombe, Devon, England Rel: Wife Occ: Station Master Wife William BACKMORE U 7 M Fremington, Devon, England Rel: Son Occ: Son John B. BACKMORE 6 M Fremington, Devon, England Rel: Son Occ: Son Annie B BACKMORE 4 F Fremington, Devon, England Rel: Dau Occ: Dau Mary J.B. BACKMORE 3 F Fremington, Devon, England Rel: Dau Occ: Dau James BACKMORE U 9 m M Fremington, Devon, England Rel: Son Jane GARD U 16 F Chulmleigh, Devon, England Rel: Serv Occ: Dom Serv