Everyone in this thread is conflating/misunderstanding various things and seems a little misinformed.
"Detention without trial" is a thing in the UK, as well as the US, Canada, and many (most?) other countries, even those considered non-authoritarian or whatever, for lots of crimes, not just politically convenient ones. This isn't a new thing because of growing fascism, it's literally the distinction between "jail" and "prison", or what the bail system is for. Court systems don't have the capacity to try everyone immediately upon arrest, and in various ways, look to balance that with the right to a speedy trial, the right to a presumption of innocence, justice, and public safety.
(I'm not making any judgement on the balance Britain is striking in this particular case, which sounds bad!)
But what OP is pointing out as problematic in Singapore's case is 1) detention without even being charged with a crime, which is what the UK government website linked above says is forbidden beyond a relatively short time frame and 2) the absence of any kind of a right to a speedy trial.