At 11.11 a.m. on Wednesday, August 11th, the moon will completely overlap the sun for 126 seconds providing tens of thousands of visitors to Cornwall and south Devon with a breathtaking natural phenomenon few are ever likely to see again. The last total eclipse visible in Britain lasted just 25 seconds 72 years ago and then, nearly three million people flocked to the north of England to see what one newspaper described felt like "it was the end of the world".
When the eclipse comes to Devon and Cornwall, a rapid plunge in temperature and a 70-mile shadow cast across the peninsula could make it feel like the end of the world all over again.
In large parts of Ireland there will be areas of 90-95 per cent totality, but when it comes to eclipses it's totality that counts.
Some 200 eclipse-chasers have paid up to £1,500 for seats on a Concorde flight which will follow the eclipse at speeds of up to Mach 2 from a spot out in the Atlantic - the supersonic aircraft will follow the central line of totality as it passes over Land's End before returning to Stansted Airport. It will be the first commercial flight to attempt to chase an eclipse and at least another 2,000 planes are expected to be in the skies over Britain's west coast on the day of the eclipse.
Even if the eclipse is not fully visible through the cloud, the tourist opportunity in Devon and Cornwall is unprecedented, with up to two million people, mainly between the ages of 16 and 24, expected to travel to Cornwall the area.
In the days leading up to the eclipse, the west coast expects 12,000 people a day to travel to its picturesque towns and villages, spending up to £900 million.
Among the visitors will be thousands of schoolchildren who have studied the eclipse in the classroom this year, and, on latest figures, up to 100,000 people from the US and Japan who booked hotel rooms many years ago - before most people in Cornwall had given a second thought to this spectacular event.
Just over a year ago a consortium of business interests, along with Cornwall County Council and the European Union, had the eclipse very firmly in its thoughts when it appointed a straight-talking, former infantry brigadier to co-ordinate eclipse day. The battle plan has taken shape at his farm on Bodmin Moor where Gage Williams has applied his military training to every aspect of planning for the millions of visitors.
"The more I've spoken about this event, the more mesmeric it becomes," says Williams. "We've left the scaremongering behind that Cornwall was going to be very pricey and that it would be overcrowded. The message is getting through to come early and stay late. Cornwall and south Devon will be busier this year but, if you do a bit of research, you will be here for a spectacular event."
Hundreds of extra ambulances, medical motorbikes and two additional air ambulances will be on call during the week of the eclipse. Doctors believe damaged retinas could be the commonest type of emergency if people ignore warnings not to look directly at the sun.
Williams has been travelling the region since last April, advising business and community leaders how to prepare for eclipse week. Supermarkets will be stocking extra food in preparation for a rush of shoppers on the Saturday before the eclipse, and a computerised traffic information system has been drawn up.
With just 33,000 beds in B & Bs and hotels largely booked by now, caravan and camping sites have been earmarked by local businesses and many visitors will have to stay in tents rather than hotels. Williams has also warned of unpredictable numbers of small boats in Cornwall's waters.
But Williams says watching the event is a chance of a lifetime. "It's very unpredictable because of the weather," he says, "but it's rather like Patrick Moore says when he sums up this event - seeing a partial eclipse when there is a total eclipse available is like going to the opera and standing outside. Why miss it or see a partial eclipse when you can come down here and see the whole thing?"