Prior to 1 January 1901 – locations in British Malaya with an astronomical observatory would adopt the local mean time based on the observatory's geographical position. Penang, Malacca and Singapore all had their own observatories; hence, the three Straits Settlements had their respective local mean time, with minutes of differences amongst the three locations.
1901 – On 1 January 1901, the Singapore Local Mean Time (Singapore Mean Time) was adopted by Straits Settlements and Federated Malay States as the Standard Time. This was introduced because railway, postal and telegraph services were becoming more common, and a single standard time will ease scheduling problems. Singapore was chosen because it was the administrative centre for the SS and the FMS then.
1932 – 12 years after the 1920 introduction of the Daylight Saving Bill, the same bill was reintroduced to the Legislative Council. One of the original reasons for dropping the 1920 bill was the argument that 30 minutes was too much change. Therefore, in 1932 the proposed shift was reduced by 10 minutes, down to 20 minutes ahead of the mean time of the 105th meridian. This was a compromise, which was perceived to be more acceptable to the overcautious Legislative Council members. After 2 debating sessions, this bill was passed and became Ordinance No. 21 of 1932. The short title was Daylight Saving Ordinance, 1932. This was to come into force on the first day of January 1933 and was to be in force during the year 1933.
1933 – 1 January 1933, the Daylight Saving Ordinance came into effect on New Year's Day. This ordinance as passed was in effect for the year 1933 only. Daylight Saving Time was 20 minutes faster than Standard Time, i.e. UTC+07:20 hours ahead of Greenwich Mean Time.
1934–1935 – For the years 1934 and 1935, the Daylight Saving Ordinance in 1932 was extended throughout both years by gazette notification.
1935 – In 1935, the Daylight Saving Ordinance in 1932 was amended by Ordinance No. 5 of 1935—The Daylight Saving (Amendment) Ordinance, 1935. The year limit 1933 was removed, turning the ordinance into permanent effect without the need for the Governor to declare any extensions. The time of UTC+07:20 hours ahead of Greenwich Mean Time became permanent Standard Time with this amendment. The Survey Department since 1935 by Annual Report advised readers to adjust their clocks appropriately by 20 minutes for the year 1936.
1936 – The Daylight Saving Ordinance became Chapter 170 in the 1936 edition of the Laws of the Straits Settlements.
1941 – In 1941, the Daylight Saving Ordinance was amended yet again by Ordinance 33 of 1941. Daylight Saving Time would henceforth be 30 min ahead of the mean time of the 105th meridian (10 min more than the original DST), i.e. UTC+07:30 hours ahead of Greenwich Mean Time. This came into effect on 1 September 1941. Interesting to note that this was the original DST proposed in 1920 and was met with much opposition then.
1945 – 12 September 1945, Japanese formally surrendered in Singapore. British Malayan Time reverted to "pre-invasion" standard: UTC+07:30 hours ahead of Greenwich Mean Time. The exact dates for the change to and from Tokyo Standard Time have not been ascertained yet. The dates given here are based on educated speculation.
The Malaysian government declared that people in West Malaysia (Peninsular) would move their clocks ahead by 30 min to match the time in use in East Malaysia (UTC+08:00 hrs an UTC+08:00:00 ahead of Greenwich Mean Time) on 31 December 1981. However, many found this to be awkward, as most of the population (roughly 80%) live in Peninsular Malaysia rather than in East Malaysia (on Borneo). The time was switched on 1 January 1982 at 6:00 am (old time) to 6:30 am (new time).