This road is called "Trewinnard Grove"

Malpas Ferry Terminal is not where shown (which are private moorings), it is at the jetty adjacent to the village name "Malpas" on the map.
Also the pontoon shown lying off Malpas is now extended to the jetty at the shore (see the Google Maps satellite view).

This road is not named Higher Trehaverne north of this point, it's just an unnamed country road.