Well I can't manage your challenge...but my vision of a maximum Singapore.....
Say the BEIC Indian mutiny is about independance(perhaps backed by the military-dominating Sikhs), not civili war, and it is somewhat succesful, driving the BEIC in most cases to the coasts or coastal ports.......
Thus the BEIC degenerates from an actual empire-company in the style of the DEIC, to a simple trade comopany. It is not disbanded, for some reason, and instead decides to compensate its loss with a British backed opening of China and Japan. Thus the East Asian trade becomes more important then the Indian trade, and Singapore becomes the most important port of the BEIC, and its "capital". So we see much more immigration to Singapore, which is developed, its inhabitants educated, minimal European settling(but dominated by Chinese like OTL).....
By 1900, it has grown to become one of, if not the most important trading port and route in the world(though the Suez, New York, and some European cities probably trump it, I'm not sure if it can be otherwise at this point). Their has also been rather more Chinese settlement in Malaya(where they make 40/60% of the pop.) and North Borneo(where they make up 70-85%).
It is larger then any other city in the non European world. The people of Singapore are educated, and the island firmly industrialized. The BEIC/Britain(if it has taken over at this point, which would be dtrimental to the challenge) have made a thing out of educating the populace of Singapore(and encouraging "equality" seeing as their are next to no Europeans) so as to make it more profitable, and this strategy has succeeded so much, it has also taken place in Malaya, North Borneo and elswhere(though not to the same extent). Singapore is, quite frankly, as developed, if not as large, as London.
By 1950 the independance era still comes along, and a incredibly large and wealthy Singapore becomes and independant and democratic republic. It is the capital of a wider federation including Malaya and North Borneo, the strait coast of Sumatra, and the rest of the Malay peninsula. Whats more, a Leuw Kwan Yeuw analogue comes along.
By 2000, the Singaporeon federation(named after the strait, not the city), is doing incredibly well, with the guiding hand of a political Bismark equivalent who is still alive, a booming economy(the territory was already first world throughout most of its territory by independance, has the Brunei oil, and total control of the strait), and a effective democracy.
Singapore has needless to say benefited, having all the advantages of today and more, with a rather larger population, cheap oil, a headstart in industrialiszation in the modern era allowing it to devote its development to other corridors, and being the capital of a large territory(and thus the hinterland neccesary for full develppement). It is the most well educated city on the planet, famous for its culture, its focus on building up, its recent move towards renewable energy, and being essentially the the most mordern(indeed post-modern compared to the rest of the world) city on Earth, the trade cpaital of the world. The federation is even sometimes considered a great power.
Yes, that is almost ASB, but noone said Nappy's challenge was plausible....that was the best and most plausible I could think of.
