That was also when there was a major to do, which I considered a tempest in a teapot, about where to do customs checking when catching a train in Singapore going to Malaysia. Up to that time you left Singapore and entered Malaysia when going onto the station platform in Singapore, and did the reverse on the return. Singapore wanted, and ultimately got the checking to move to a point at the border. There was also the issue of the status of the railway itself. So far as Malaysia was concerned, the Railway owned the right of way and station outright. So far as Singapore was concerned, the land and station were held by Malaysian Railway as an easement for the purposes of operating a railway only and they could make no use of it for non-railway purposes. I do not know how that one ultimately played out, but I would suspect that Singapore got their way.
Well the Singaporeans basically kicked the Malaysian immigration officials out across the Straits of Johore to Johore Bahru. The last time I took the train from Singapore to Malaysia about 10 years back, the Singapore immigration folks would stamp exit in the passport at Singapore station in Tanjong Pagar, but the Malaysians get their hands on the passport to stamp entry only after you cross the Straits of Johore on the causeway and get to Johore Bahru.
The latest they have been talking about dismantling the KTMB (Keretapi Tanah Melayu Berhad - the Malysian Railway) MG line back to Woodlands where they propose to build a new station adjacent to the Woodlands MRT stop. So if it comes to pass, this would be the final eviction of the Malayans from Singapore in a manner of speaking.
By the way, for the info of others, in Singapore all signs are multilingual in four languages. In Malaysia they are not. The station sign on the platform in Singapore was in only one language, and it said, Singapura, which is the Malay was of spelling Singapore. At least, Malaysia uses the Roman alphabet. Also, to the relief of the English speaking foreigner, a lot of, maybe most of the people have some knowledge of English.
Also all announcements on Singapore's wonderful MRT system is in four languages for everything - English, Malay, Chinese and Tamil.
Seriously, Singapore's MRT puts most western subway/Metro systems to shame. But then again. KL's (Kuala Lumpur) Metro, LRT and suburban system is not too shabby either. But still, it is one notch below Singapore's
Incidentally Singapore is anglicized form of Singha Pur which in north Indian languages, and indeed in Malay too means Lion (Singha) City (Pur).
BTW, the Malaysians use the Roman alphabet for the written form of their language because before that they did not have a written form of the language. It was just as spoken language. Which is quite curious since their northern neighbors, the Thais had a pretty old written script and a language with lots of borrowed words from Sanskrit pronounced differently, sometimes in mutually unintelligible ways, until you figured out the transition rules. And then it becomes somewhat possible to understand most of Thai to someone that knows or understands a north Indian language.
And finally United Malaysia did exist for two years from 1963 to 1965, and then the final breakup happened, which as George says is represented quite differently in the history books of the two countries involved.