It appears that the long-awaited Article 50 trigger, officially beginning the Brexit process, will take place next Wednesday, March 29, because moments ago a Theresa May spokesman confirmed a report in the UK's CityAM, reporting that Article 50 will be triggered next Wednesday.

• U.K. TO TRIGGER BREXIT ON MARCH 29, MAY'S SPOKESMAN SAYS

Britain’s ambassador to the EU Tim Barrow told the office of European Council President Donald Tusk that Britain will trigger Article 50 of the Lisbon Treaty, Mrs. May’s spokesman said. He said he expects talks to begin promptly, but that the U.K. understands the 27 EU countries will want time to deliver their response. Slack said that “after we trigger, the 27 will agree their guidelines for negotiations and the Commission’s negotiating mandate” and added that “president Tusk has said he expects an initial response within 48 hours. We want negotiations to start promptly”

EU Council president Donald Tusk is now expected to respond formally in the next two days, although the detailed EU negotiating position is not expected to emerge until later in the spring.

David Davis, the UK’s Brexit secretary added that "The Government is clear in its aims: a deal that works for every nation and region of the UK and indeed for all of Europe – a new, positive partnership between the UK and our friends and allies in the European Union."

As the FT adds, the pre-announcement of the timing of the Article 50 letter is partly aimed at preparing financial markets for the formal start of the Brexit process which will last at least two years.Downing St has been anxious in recent months to counter the risk that major Brexit announcements are inevitably accompanied by falls in the value of the pound. 

Meanwhile, cable has not reacted to the news, with the pound trading at a three-week high against the dollar at $1.2410 on Monday.