Blencogo NY 193 480

Blencogo NY193480  Blencoggou 1190, Blengoggou 1255, Blenghogou 1279, Plenecogo 1195, Blencogau 1220, Blencogou 1278, Blenecoghow c. 1270, Blencoggehow

PNCu notes Ekwall's suggestion this is blaen + cog "cuckoo top", + Norse haug(r), but then prefers the plural blaen + cogou and compares the Cornish Talcogou, Talgogou 1302. That seems right.  

A late borrowing because medial -g- did not appear until early Middle English due to Norse borrowings where the Norse medial geminate /gg/ developed into /g/  - where the English /gg/ became /dʒ/.

Geographically, Blencogo Farm stands on top of a gentle rise at 43m above sea level.