Just when or how Britain leaves the EU comes down to another PM's big gamble

Over recent years, all roads in British politics have led to one thing, Brexit-the issue that has dominated the political landscape since summer 2016.

But for all the sound and fury and careers that have risen and fallen in its shadow, Britain's exit from the European Union has still not happened.

According to Boris Johnson, the third prime minister to have had to wrestle with the issue, do or die, come what may, Oct 31 would be Brexit Day. But it was not, as the date for Britain's departure was put back to January, stretching it out into a fifth calendar year.

So what is the pathway that has led British politics to where it finds itself now, and where, depending on the outcome of the coming election, it may or may not remain for some time yet?

Britain's future in the EU became a live political issue in January 2013, when, having lost two MPs to the Eurosceptic United Kingdom Independence Party, then-prime minister David Cameron promised a referendum on the question by the end of 2017 if his ruling Conservative Party won the 2015 general election, which it duly did.

In December 2015 assent was granted to a parliamentary bill for a referendum on June 23, 2016, with politicians free to pick sides. Leading campaigners for Remain included Cameron and then-home secretary Theresa May.

Prominent supporters of Leave included Michael Gove and Johnson, who said he reached his decision "after a great deal of heartache". It was later revealed that he had also written a lengthy newspaper article advocating the benefits of remaining, as he considered his options.

When the referendum came, out of a potential electorate of 46,501,241, turnout was 72.2 percent, and of that number, 51.9 percent had voted to leave.

Johnson and Gove declined to fill the leadership gap left by the departing Cameron. Unexpectedly, former Remain supporter May found herself tasked with the next stage of the process.

Leave's big guns not putting themselves forward was significant, because it revealed the problem that has dogged Brexit ever since; the lack of a plan for what Brexit actually meant.

In November 2016, the High Court ruled that the government was not free to enact the legislative procedure called Article 50, which begins the process of leaving the EU. It must involve the Parliament, the court ruled.

After parliamentary consultation, in March 2017 May triggered Article 50 and weeks later called a snap general election on June 8, hoping a new Parliament would prove more obliging and sort out Brexit more quickly.

It backfired disastrously, with the Conservatives winning fewer seats, and only staying in charge with the support of Northern Ireland's Democratic Unionist Party, or DUP.

Over subsequent months, then Brexit secretary David Davis made tentative progress in his negotiations with the EU, but in July 2018 he quit the Cabinet, saying he was "unpersuaded" that London's approach "will not just lead to further demands for concessions" from Brussels.

Days later, he was followed out of Cabinet by Johnson, then the foreign secretary, who said May's plans would mean Britain having "the status of a colony".

In November 2018, there was a breakthrough as May said that Cabinet had agreed a draft Brexit withdrawal agreement, which she called "the best that could be negotiated".

But her relief was short-lived as Dominic Raab, Davis's successor as Brexit secretary, resigned, saying he "cannot in good conscience support the terms proposed", and prominent Brexit-supporting backbencher Jacob Rees-Mogg submitted a letter of no confidence in May's leadership.

The ballot on May's party leadership in December saw the parliamentary vote on her deal postponed until the new year, and although she survived the leadership vote by 200 votes to 117, so many MPs voting against her was damaging.

May's Brexit deal went before Parliament in January 2019, when it lost by 432 votes to 202, the largest margin of defeat for a sitting government in history, and again in February and March, by smaller but still significant numbers of votes.

At a subsequent European Council summit, European Council President Donald Tusk said the UK had agreed to a "flexible extension" to Brexit until Oct 31. But following a poor performance by the Conservatives at the European Parliament elections in May, the prime minister announced she would step down.

Johnson, chosen as the new party leader, promptly suffered a string of defeats in Parliament, and for all his "do or die, come what may" rhetoric about Brexit happening on Oct 31, the deadline day has passed again.

Johnson has secured a new deal with the EU, but it is utterly acceptable to the DUP, and his desire to rush it through Parliament provoked wider resistance. He called a general election-the third in four years-to try to clear the political blockage. Just like May gambled on doing. That poll is on December 12.

The government hopes a change of Parliament might produce more positive results. The Brexit saga continues.