Feature: 15 hours that might change British history

At 7 a.m. local time (0600 GMT) on Thursday, more than 41,000 polling stations across Britain opened their doors for a referendum that might change the course of British history.

At many polling stations, people appeared and queued before they were opened, trying to be among the first to vote among the 46.5 million eligible voters, who will decide whether Britain should remain or leave the European Union (EU).

The polls will be closed at 10 p.m. (2100 GMT). Local results will be announced as soon as they are confirmed, the first expected around midnight, but the bulk between 3 a.m. and 5 a.m. (0200 to 0400 GMT) on Friday.

Television pundits will be looking for clues to interpret the results. One of the first major conurbations to declare is expected to be Sunderland in Northeast England, where the anti-EU party UKIP has a lot of support. The margin of the votes there could be an early hint of what may follow.

Jenny Watson, chair of the Electoral Commission, has said the turnout in the referendum is expected to be high, possibly around 80 percent, making it the biggest poll in British history.

In her role as chief counting officer, Watson is expected to announce the results to the world, live on television, around 7 a.m. Friday.

The Manchester Town Hall will be the focal point for her historic announcement.

Watson admits she too is eagerly waiting to see the all-important results.

Hours before the official announcement, possibly around 3:30 a.m. to 4 a.m. (0230 to 0300 GMT), there may be clues about the outcome as results from around the country are analyzed by political and electoral experts.

But until Watson, in her official capacity, declares the final result, nothing can be set in stone.

Early Friday, politicians will re-enter the scene, to absorb and digest the result and comment on repercussions of a decision taken by the British public. Endi