Thomson Ridge is located off Thomson Road.  Old Singapore map shows very little feature around here - Heap Hoe Rubber Factory (next to Jasmine Road) up north and heading south, Thomson Village, a Chinese cemetery, Little Sisters of the Poor.  The estate north of Hepa Hoe Rubber Factory (Gardenia Road, Jamine Road etc) was probably developed by Bukit Sembawang.   But I am not sure who developed Thomson Ridge Estate.

Looking at the maps from OneMap, the area is in Mukim 15.  (A mukim is essentially a sub-district).  Within the mukim, each land parcel is assigned a Lot number by the Singapore Land Authority.  The land parcels starts from Mk15-00104X and ends at Mk15-02341W.  The 2 roads running providing access to the dwellings here are Thomson Ridge which short of loops around the ridge and comes back to join Jalan Lembah Thomson.  The area is designated for 2-storey semi-detached dwelling and 3-storey mix development (along Jalan Lembah Thomson). Currently there are about 106 semi-detached, 66 terraced dwellings and 5 shophouses.  Some of these houses are as in the original.