The Queen gave royal assent on Thursday 16 March to the recently passed Brexit Bill, paving the way for Theresa May to trigger Article 50, the process of leaving the EU.
The Prime Minister has repeatedly given March 2107 as the time when she will formally begin the process, but has not given an exact date.
The Bill was passed by the House of Commons and the House of Lords, after MPs were forced to vote again on two amendments – on guaranteeing the rights of EU citizens to stay in the UK post-Brexit and allowing a final "meaningful" parliamentary vote before Article 50 was triggered.
It was previously believed that May might trigger Article 50 and begin the two-year Brexit process straight after MPs voted on the two amendments to the Brexit Bill, with 14 March having been the date pencilled in.
However, 10 Downing Street said that May will more likely trigger Article 50 towards the end of the March. It dismissed suggestions that Scottish National Party leader Nicola Sturgeon's announcement of her plans to hold a second Scottish independence referendum had any influence on the decision to push back the date.
May is now reported to have set 27 March as the date for when she will notify Brussels of Britain's plans to begin their exit from the EU.