Tinhay is not on the original, but FMP have used it in their 'version' of the address.
FMP also include a map of the location for 1939 addresses. In this case, the 'pointer' is very close to Lifton Railway Station, which is to the east of the Town, and some distance from Brentor. Above the station and to the NW is an area marked 'Tinhay' on the map.
I think FMP's idea of the 'local area' is inaccurate, and Tinhay is a red herring.