The Shetland Oil Disaster: Experts relying on guesswork to gauge damage: Six days after the Braer hit the rocks, the full extent of the disaster is still not clear. Nicholas Schoon reports

(First Edition)

WILL IT BE Britain's worst environmental disaster? Do not trust anybody who claims to know.

No expert has a remotely reliable estimate of how much oil has leaked, nor how much damage to the islands' economy or the life in the seas around them. More important is the question of how much more oil will be released.

Smashed by waves and slowly disintegrating, the Braer is an environmental time bomb with an unknown period left on the clock. The seemingly incessant storms may, at any time, cause breaches which would release more of the crude oil still in its tanks.

Be that as it may, the army of journalists and broadcast technicians which flooded in during the first four days is now just beginning to move on, with the foreign press heading the exodus. The struggle now is to find a place on a flight out of Sumburgh Airport rather than a flight in.

Cancellations caused by the weather are making it harder to leave. This allows some of the 22,500 islanders a little longer to benefit from the extra income which the influx has brought at what is usually the quietest time of year.

With probably more than 1,000 journalists on the island at the peak, along with volunteers and the experts and technicians dealing with the spill, more than pounds 1m will be injected into the economy.

Predictably, some islanders have responded to the huge demand for accommodation and transport by raising prices steeply. One budget bed-and-breakfast establishment which would normally be shut during the winter has opened and is charging pounds 50 per night for bed alone. Yet, for the most part, the islanders have met the invasion with courtesy, kindness and tolerance.

The clean-up and containment operation has been almost completely thwarted by bad weather. Its most impressive feature is the way the press has been kept informed of what is - or is not - happening. Banks of telephones have been set up, and broadcasters have been provided with office space, and weather, wildlife and slick bulletins in abundance.

A few of the press contingent have misbehaved: photographers have asked mothers and children to pose wearing breathing masks which they provided, or clutch hankerchiefs across their faces, to show how frightened they are of the oil fumes. And yesterday, Greenpeace pleaded with journalists not to walk along oiled beaches because they were allegedly scaring birds into flying off, back into the polluted water.

The press was startled when Lord Caithness, the shipping minister, said the damage was localised. He explained that many outsiders had been given the impression that the entire Shetland coastline was oil covered.

It is true that only a small fraction of the coastline and land area has been damaged to date. It is also true that the damage on land will be confined to Shetland, a small, remote island community about which most Britons know little.

But ask any of the ecologists and volunteers collecting hudreds of dead birds, fish and now seals off beaches, and they will say unequivocally that something very big and bad has happened.

'It's an ecological disaster of great significance,' said Dr Peter Evans, an expert on sea mammals at Oxford University, who is one of the coordinators of the efforts to save surviving wildlife and collate information on the casualties.