Roger Mosey, BBC head of Olympics coverage, told a breakfast briefing that the corporation expected viewing figures to be on par with recent Olympic Games, even though these Games are to be held locally.
Mosey said 75 per cent of the UK audience watched the Beijing Olympics despite time zone issues and 80 per cent watched the Athens Olympics, which were held in a similar time zone.
"We are expecting 75 to 80 per cent to be the broad figure (for London)," Mosey told an Around The Rings meeting, as scores of international global broadcasters descend on London this week for briefings.
"Interest is building slowly, evidence from the past host cities is that it takes off in the final year."
He said at the moment, most interest in the Games was not from London or the South East but from Northern Ireland, a fact attributed to that region's younger audience.
Mosey said the main BBC coverage would be on BBC1 and that all competition would be shown live through 24 dedicated internet channels. He admitted that the coverage might be "drum-beating" but said if it was, it would be in the context of the UK having a multi cultural audience.
Gary Fenton, the Olympics chief of the Australian rights-holding network Channel Nine, said the notorious British weather was not an issue for broadcasters.
He said broadcasting in inclement weather tended to soften the impact of the weather to an audience.
But he revealed that during the Sydney 2000 Olympics the weather was so fine, the fog rolled in preventing a helicopter from beaming overhead shots of the men's marathon race.
Both Mosey and Fenton said the biggest challenge for the organisers was transport of officials, athletes and spectators.
"Getting them in and getting them out, we are not sure how it will work," said Fenton.
And the event, apart from the opening ceremony, which will attract the biggest audience? Mosey and Fenton agreed on this too - the men's 100m final.
http://www.telegraph.co.uk/sport/olympics/8659558/London-2012-Olympics-BBC-braced-for-mammoth-viewing-figures.html