The camp in favour of Britain's exit from the European Union (EU) edged past the 'Remain' camp for the first time in the referendum count today.
The "too-close-to-call and knife-edge" prediction of the opinion polls seemed to hold true as Leave grabbed 52% of the vote to Remain's 48%, overturning a similar lead held by the 'Remain' camp earlier on in the count.
The broad trends indicate that the side in favour of 'Brexit', or Britains exit from the 28-member economic bloc, was showing a stronger performance than initially expected.
Many of the areas expected to be strongly in favour of Remain were not as definitively against Brexit, with London throwing up a slimmer anti-Brexit vote than predicted.
"At this very early stage, the Leave side has done much better and even looks like the favourite to win the referendum," BBC polling expert Prof John Curtice said.
Northeast England and Wales seem to be backing Brexit, while Scotland and Northern Ireland appear to have opted for Remain - but millions of votes still remain to be counted in the referendum, which has registered a 71 per cent turnout - higher than the 2015 General Election.
The markets reacted to the uncertainty with the pound surging as the polls closed last night, before falling dramatically to its lowest point since 2009.
Earlier, Gibraltar had been the first of the 382 local counting areas to declare, voting overwhelmingly in favour of staying in the EU, as had been expected.
The territory on Spain's southern tip voted 95.9 per cent "Remain", against just 4.09 per cent - 823 votes - for Brexit.
Unlike at a General Election the results in individual areas do not count as it is the overall number of votes cast for one side or the other across the country that will determine the outcome.
The side which wins more than 50 per cent of the votes at the end of the count would be considered to have won.
The final national result is to be officially declared by the UK Electoral Commission's chief counting officer, Jenny Watson, from Manchester Town Hall.
She had earlier announced that her verdict is expected around "breakfast time" this morning (local time), triggering speculation over whether it would be an early breakfast or a late one - based on how the counting trends pan out.
Brisk voting marked polling day yesterday as the results remained too close to call till the very last minute.
Experts had predicted that a high turnout would benefit the Remain campaign. The final announcement will bring to a close a fever-pitched and highly-strung campaign by both the Brexit and Remain sides.
There has been much speculation about how the final outcome would impact David Cameron's own political future as Prime Minister.
While he has repeatedly stressed that the 2015 General Election has given him the mandate to continue irrespective of the result, the bitter campaign had exposed a deep divide within his own Conservative party.
However, over 80 Eurosceptic MPs from his party, including
leading Vote Leave campaigner Boris Johnson and Indian-origin minister Priti Patel, moved quickly to calm the internal turmoil by urging Cameron to stay on as PM in a letter delivered to him soon after the polls closed last night.
"We who are supporters of Vote Leave and members of the Conservative Party thank you for giving the British people a choice of their destiny on 23 June. We believe that whatever the British people decide you have both a mandate and a duty to continue leading the nation implementing our 2015 manifesto," the letter states.
Both sides of the campaign had urged the over 46 million registered voters, including 1.2 million British Indians,to brave rains and flooding to cast their votes.
In some areas, booths had to be shut and moved to a different location due to water-logging but the general spirit remained on a high throughout the day.
Cameron voted early near Downing Street after he had closed the campaign with the message to voters to "get out there and vote Remain" and reject the "untruths" of the camp in favour of Brexit or Britain' s exit.
On the opposing side, former London mayor Boris Johnson, heading the final drive for the Vote Leave campaign, had hoped today could mark the UK's "independence day".
While the Remain camp, led by Cameron, had campaigned for economic certainty and safety of jobs, the Brexit camp had made their case as a vote to take back control of the UK's borders and finances.
Immigration had been the central theme throughout and expected to swing most of the votes in favour of Brexit.
Indian-origin voters, the biggest ethnic minority group in the UK of an estimated 1.2 million, had reflected a divided house in line with the country-wide knife-edge divide in the four-month-long referendum campaign.
A British Election Study (BES) had found that 51.7 per cent of them were against Brexit, compared to 27.74 per cent in favour of leaving the economic bloc.
However, a significant percentage (16.85 per cent) of those who fell into the "Don't Know" category in the study last month were expected to hold the key to the results.
The referendum ballot paper asked the question: "Should the United Kingdom remain a member of the European Union or leave the European Union?" Voters have the option to mark a cross next to either "Should remain in the EU" or "Should Leave the EU," with the winning side needing more than half of all votes cast.
In a departure from the norm, no major broadcasters had commissioned any exit polls over concerns about accuracy.
The bookmakers, however, had seemed more confident about a Remain vote, and saw a flurry of late activity as the referendum became the biggest political betting event in history with an estimated100 million pounds being wagered.
The financial markets had also signalled a more stable result throughout the week with the Pound Sterling holding strong.
Numerous hedge funds had commissioned their own exclusive exit polls at a cost of up to 500,000 pounds, which asked people how they voted on their way out of polling stations.
The results were intended to help traders get an insight into the way the vote would go ahead of the public, with these polls remaining private.
After polls closed at 10 p.m. yesterday, sealed ballot boxes were collected and transported to the count venue for each of the 382 local counting areas.
These represented all 380 local government areas in England, Scotland and Wales, plus one each for Northern Ireland and Gibraltar.
