To be clear, there wasn't a no-deal Brexit in the end. There was what was originally called a hard Brexit (https://en.wikipedia.org/wiki/Brexit_withdrawal_agreement), but a no-deal Brexit would have been far worse.

R (Miller) v The Prime Minister (not to be confused with R v Miller, or R (Miller) v Secretary of State for Exiting the European Union (the solution here is clearly to just stop naming people 'Miller', to avoid further confusion)) was probably ultimately more important in its precedent than its concrete outcomes, though, yeah.