The affable and savvy sitcom writer and campaigner was pipe-smoking and poshly-spoken; he owned a large house in Surrey and sent a son to Eton. He was either a naive hero indifferent to risk, or a flawed maverick who made fatal misjudgements. "Ken was no saint", says Donu Kogbara, a London-based Ogoni journalist friend of his. "He was tremendously charismatic and sometimes very nice", she remembers. But she believes he lost touch with reality as he was wooed by starry names in Europe and the US.

Ken Saro-Wiwa became a darling of the greener sections of London liberal society, but had been on the federal side during the Biafran civil war, and would thus have been reviled by liberals then. It has been argued that he was a federalist because he thought only a strong state would defend minorities like the Ogoni. Anyway, he is widely believed to have feathered his nest when managing the Niger delta oil port of Bonny during the civil war. Ken finally and fatally enraged his country's military regime by demanding greater autonomy for the people living in a patch of the swampy Niger delta. Given the politics of the country, the more strident of these voices were bound to be silenced. He seems to have been caught out by the military's haphazard alternations between permissiveness and oppression. And he did not help his cause by unleashing undisciplined and deeply disaffected young men on moderate former colleagues in the struggle, four of whom were murdered at a rally. Donu Kogbaru believes her own father, one of the moderate leaders, was lucky to escape with his life. "I'm accusing Ken of incitement to murder", Donu Kogbaru insists, when pressed.

The West was interested in his campaign because it was directed almost as much at the Shell oil giant as it was at Nigeria's regime. Shell was the obvious target for an ironic reason, as most of its Nigerian critics freely admit. The oil company is perhaps the most respectable institution in Nigeria.

"We've been here a long time and we expect to be here a long time", says Brian Anderson, the Nigerian-born white who runs Shell's operations there. Shell started producing oil from the Niger delta 40 years ago. It was in Nigeria when the place was one of the bright stars of the continent and expects to be there when and if hope returns. In the meantime, like any large firm there it funds armed police seconded from the state for the defence of its people, and necessarily deals with authorities of whom it strongly disapproves.

Ken realised Shell was amenable to pressure. It operates as a thirty percent, and the largest private, shareholder in a Nigerian joint venture company, Shell Petroleum Development Company (SPDC), alongside Elf and Agip, with the Nigerian state oil company owning 55 percent. In the delta, you see the Shell sign everywhere, but it stands over facilities substantially owned by the Nigerian state, which must put in 55 percent of the capital expenditure required to keep production flowing - and clean. Shell's biggest problem is in wringing that share from the state.

SPDC produces about a million barrels of oil a day, half the country's total which contributes in a good year around $9 billion dollars to the national exchequer, or three quarters of the total government revenue (and about a third of the country's GNP). Some of the money is salted away by the country's leadership and their friends. Little of it reaches the delta where all of it is produced, and where six million people live in a soggy region of farms, forests and swamp about the size of the Republic of Ireland. Even less than its fair share reaches Ogoniland, where half a million of Ken Saro-Wiwa's compatriots people live in an area of about 1000 sq kilometres.

The lively Nigerian economist Patrick Utomi once proposed that the oil ought to be given to the ruling elite once and for all - in return they might give Nigeria back to the people. The Economist Intelligence Unit's regional report notes that the country's economy collapsed during the oil boom: too many important players gave up conventional work and concentrated on trying to cream off a share of the bonanza.

Arguably, none of this is Shell's fault: as Brian Anderson never tires of stressing, three percent of the revenue SPDC pays the Government was supposed to come back to the producing areas. It's a sum close to Shell's 3.2 percent share of the oil dollar, and is a sliver of the country's average 75 percent share of the barrel's worth. If the arrangement had worked, the delta might have become a fine area in a fine country. "The money was not fully spent, and it wasn't wisely spent", Anderson insists, in a code which speaks of corruption and waste.

A meeting with local chiefs at Sapele township in the north west of the delta has the erudite community spokesman Vin Kariks Ekariko rattling off a list of health and environmental effects many of which probably aren't real or could not be caused by the oil industry. After the meeting, and in private, a local chief thanks the Shell people for the scholarships, the education schemes, the community hospitals and all the rest that the company has done locally - and much of it long before the disturbances of the early 90s. He wants more, and knows that in a better society politics, not begging, would sort things out. He does not say - but it's true - that community leaders are usually as keen to cream off their share of the booty as anyone else. Shell spends about $20m a year on community projects (and eight times more on environmentally-orientated equipment renewal). "Things are back to front here," says Anderson. "The Government's in the oil business and we're in local government". He believes privatisation is inevitable in the end, and looks forward to it.

Flying over the delta in a helicopter for hundreds of miles, and visiting several noted pollution hotspots as well as observing a dozen or so oil production facilities and, crucially, the water and ground around them - it is hard to see what the environmental fuss has been about. In the delta there are plenty of rivers and creeks where there is an oil sheen. They remain a tiny minority, and the spills may as well have been caused by careless local boatmen as by the oil giant. For the most part, the delta is a vast, watery, deeply verdant region lying under skies which are ordinarily tropical. Shell occupies one third of one percent of the delta: even if it had devastated that area and ten times more besides, and it hasn't, the damage would be a fraction of what is routinely claimed by campaigners.

What then of the famous flares? Firstly, there are none at all in Ogoniland, where there has been no oil production since 1993, following community disturbances. Elsewhere in the delta, about a hundred flares waste a resource equivalent to a quarter of France's gas demand.

The flares do very little useful work, and it has been castigated by green commentators. Because oil production facilities bring people with money, locals congregate wherever SPDC has kit. Some come to live near flares, which constitute free light and a means of drying crops such as cassava.

Rightly, SPDC is committed to putting out all the flares, if possible by 2008, and about a quarter of them within three years. The latest project to harness about a quarter of the wasted gas involves deals with customers in southern Europe and 5.5bn dollars worth of new plant whose financing was a nightmare, not least because the Nigerian government, already heavily in arrears in its payments to SPDC, had difficulty raising its share.

The scheme has been an on-and-off affair for twenty years, but is now under construction. The deal was agreed in the weeks following Ken's execution and seemed to some a symbol of Shell's venality. For Anderson the position is simple: if Shell pulled out of Nigeria someone less committed would go in. The gas scheme was a sign of progress, not failure. On the revenue-addicted economy he comments, "The 'curse of oil' is a real issue - but it has brought a lot of good things. I believe very strongly that by being here we offer something for them to choose from." Besides, he adds: "No country in the world has ever left oil in the ground". It is not the observation of an angel, but then there seem to be few angels in this story. One can see the physical presence of Shell in the delta and think it tolerably benign. What is harder to sense is whether Shell has been canny - still less, whether it has been at all noble - in its arm-twistings in the Nigerian corridors of power.