BBC correspondent Mark D'Arcy looks at the Parliamentary processes ahead, should the Supreme Court rule against the government over triggering Article 50.
Tim Farron says the Lib Dems are 'back' after ousting Zac Goldsmith in the Richmond Park by-election.
Britain will not seek to obstruct closer EU defence co-operation after Brexit, Boris Johnson says.
The UK may pay to get the "best possible" single market access, Brexit Secretary David Davis says.
What we learned about the Leave result
Was Richmond Park result all down to Leave v Remain?
Key quotes from European leaders on Brexit
Scepticism at prospects of Anglo-Polish alliance
Should we give up on polling?
John Curtice on parallels across Atlantic
Supreme Court prepares for Brexit case
Profile of the woman behind Brexit case
What Brexit means for NI border?
The 11 judges who will have final say in Article 50 case