China, the country was never a colony under British rule - perhaps you're thinking of the island leased to Britain, Hong Kong.
China did have interactions with Britain, disputes over trade, access, addictive drug running, gunboat diplomacy et al. but these usually fall under British Imperialism rather than British Colonialism.
I think that's the previous posters point. The OP argued that countries were better off in the long run with British colonialism than without. I think China vs India is the counter example.
I wouldn't count China as a third world country to compare to, so that's fair enough, but also China is only doing well because it coccooned some capitalism based on English common law and its derivatives, and a limited imitation of the liberal tradition thereof. Of course it's a facade, but it works well enough to lift them out of poverty.
India you should compare to India's trajectory had British rule not occurred.
Given generally we measure poverty by how many things Western countries have invented and built, and not look to India as the leading edge of development, it's not hard to deduce India's trajectory had it never met the West. Overwhelming caste system, low tech. Hitting a local maximum and never getting out of it. A bit like what the UK might've been had the Romans never colonised it.
China did have interactions with Britain, disputes over trade, access, addictive drug running, gunboat diplomacy et al. but these usually fall under British Imperialism rather than British Colonialism.