This was on Salisbury Road, next to the KCR terminus and opposite the old Marine Police HQ.
Initially it was built as a garage. Notes from Moddsey:
The typhoon of 20 August 1927 brought down the HK and Kowloon Taxicab Company's Garage on Salisbury Road near the KCR Terminus. About 20 cars and half a dozen motor cycles were in the garage at the time of the disaster.Extensive damage was caused. HK Telegraph 22 August 1927 refers.
In 1928, foundation work for a new motor garage for Alex. Ross & Co. Ltd had begun on the same site. HK Daily Press 2 July 1928 refers. The one storey building would be completed around 1929.
In 1934, it became the TST Post Office. Moddsey again:
The move [from its first location] across Salisbury Road to larger premises was completed in November 1934 when a showroom and garage formerly occupied by Messrs. Alex. Ross & Co. on KCR property was converted into a Post Office with a large public hall with fitted counters, sorting room and records office.
The move into the new premises was intended to be temporary one until a larger administration building housing other government departments and post office could be built. Owing to the economic depression that Hong Kong was facing in the 1930s, construction of a new Post Office in Kowloon prior to WWII never materialised.