London: That ... was it? Given all the division, the turmoil, the political carnage and the economic upheaval, the most remarkable thing about this chapter in history is how unremarkably it concluded.

Slipping by late on Friday night, Britain's formal departure from the European Union had all the energy and excitement of someone who was desperate to just hit the sack at the end of a big week. Or in the case of Brexit, a very big decade.

Brexit supporters gather outside Parliament to mark the moment. Credit:Getty Images

"I voted Leave in 2016 but I really couldn't give a toss about all the celebrations tonight," said retired cook Jenny Blake, who was enjoying a pint in a pub just a few blocks away from a rally outside Downing Street and the Palace of Westminster. "It's good it is finally happening but it's not like everyone is jumping out of their skin."

The United Kingdom formally left the bloc at 11pm following 47 years of membership, however the existing relationship will remain in place during an 11-month transition period in which new trade, security and immigration deals will have to be thrashed out.