China Mail 13 May 1901. Prior to the move to Wyndham Street. Noted in a "To Let" advertisement that the office at 25 Aberdeen Street was also performing the function of a letting-out agent.
The earliest advertisement showing the address at Aberdeen Street is in the Hong Kong Daily Press dated 3 January 1901.
Date picture taken
13 May 1901
C.E. Warren at 25 Aberdeen Street
Thanks for finding this earliest January 1901 date for C.E. Warren's 25 Aberdeen Street premises. I have a 1908 Rate Book entry recording 25 Aberdeen Street as owned by the "Kirchmann Trust". John Olson snr., Charles Warren's father-in-law, had been Louis Kirchmann's executor.