Days?

> The police can hold you for up to 24 hours before they have to charge you with a crime or release you.

> They can apply to hold you for up to 36 or 96 hours if you’re suspected of a serious crime, such as murder.

> You can be held without charge for up to 14 days if you’re arrested under the Terrorism Act.

https://www.gov.uk/arrested-your-rights/how-long-you-can-be-...

but then once charged you can be held for years on remand [0], there is no limit to how long the court can take to actually getting around to holding your trial. The law says now 8 months, but (as this site says) people are held for years.

[0] https://legalknowledgebase.com/how-long-can-someone-be-held-...

Yeah, and once your speech incites people to set a hotel full of people on fire, some of them can die forever! It really makes you think.