The six days in February 1996 when the Sea Empress was spewing crude oil onto the incomparable Pembrokeshire coast were a classic case of defeat snatched from the jaws of victory.

Even when one of the most powerful tugs available arrived to take her to safety, the situation rapidly turned to farce.

None of the tug's Chinese-speaking crew could communicate with those on board the Empress.

So an interpreter had to be summoned - from a Chinese take-away in Milford Haven.

Watching from St Ann's Head the evening she eventually floated free, with no fewer than 13 tugs in attendance, I could scarcely believe that the salvors had finally got it right.

It is now clear that the Sea Empress need never have come to grief. But what about the chances of similar accidents in future ?

With increasing quantities of oil travelling by sea, it is a certainty that there will be more accidents.

Simple remedies

The increase in tanker movements means the rate at which they happen will probably rise as well.

But there are some fairly simple things which - given the political will - could both reduce the accident rate, and minimise the damage the inevitable accidents will cause.

One is to make sure that help is available as soon as something goes wrong.

The 1997 report of the government's Marine Accident Investigation Branch is relevant here.

The Braer could have taken a different route

It says: "The two large tugs under the control of the Coastguard Agency should have been mobilised and moved towards the scene of the incident soon after the initial grounding."

Yet when the Sea Empress went aground, those tugs were at their home bases - Dover, at the far eastern end of the English Channel, and Stornoway, in the Hebrides.

Had they been sent to Milford Haven promptly, the MAIB report says, they "would have made a major contribution" to the salvage operation.

Another important measure is to make sure that tankers have double hulls, so that damage to the outer hull will leave the cargo intact.

Stricter rules needed

The MAIB report says: "It is probable that oil pollution would have been avoided in the initial grounding if the Sea Empress had been constructed to the double hull design."

Given the decision to site a major oil port within the boundaries of the Pembrokeshire national park, it seems obvious to rule that only double-hulled tankers should be allowed in.

But nobody took that decision.

Spraying detergents can do more harm than good

The Sea Empress accident came only four years after the Braer went aground off the southern tip of Shetland.

She had lost power while making her way past Fair Isle towards the open north Atlantic.

And voices were raised then to ask why a laden tanker had been allowed to sail through those pristine seas, when she could have taken a different route.

There is a limit beyond which governments are unwilling to tell oil companies where their vessels may go.

Lax enforcement

There is also a limit to governments' willingness to protect the environment if it is going to cost them money.

The Sea Empress and the Braer both showed that controls on the passage of oil by sea are sometimes too laxly enforced to give real protection.

A decade ago, the Exxon Valdez laid waste to the wildlife of Prince William Sound in Alaska.

None of those accidents need have happened, or need have caused the damage they did once they had happened.

One often unremarked lesson of tanker accidents, though, is that they are seldom disasters.

The Exxon Valdez: In the wrong place ?

They provide tremendous TV footage, and images of choking seabirds make us think in apocalyptic terms.

But time and again experience shows that nature is more resilient than we realise.

Using detergents to clean oil from damaged beaches or wildlife, for example, frequently does more harm than good.

And the oil that spilt from the Braer vanished without trace, as Shetland bowed before the strongest gales for a century.

This is not to say that oil spills do not matter. They do.

But if we were really concerned about pollution, we should get far more worried about the quantities of oil pumped deliberately from ships' bilges around the world day in and day out than about the occasional Sea Empress or Braer.