Queen Elizabeth II gave her royal assent on March 16, 2017 to a Bill empowering British Prime Minister Theresa May.
The assent will permit the trigger Article 50 of the EU's Lisbon Treaty and begin the process of leaving the European Union.
A letter will be send European Council informing them of Britain's decision to leave the bloc by the end of March, following a majority vote for Brexit in last year's referendum.
The legislation now has royal assent.
The Queen's signature on the Bill allows May to invoke Article 50 at any time, starting a process that will take a maximum of two years unless Britain and its EU partners agree to extend the deadline.
May said she will address the British parliament to inform lawmakers that she has triggered Article 50, and an initial response is expected from the European Commission within 48 hours.
Lisbon Treaty: Know More- Signed : 13 December 2007
- Signatories : EU Member States ( EU-27 )
- Effective : 1 December 2009
- Languages : 23 EU languages