In September 1969, the superintendent on duty aboard a North Sea drilling rig decanted the first crude oil found off Scotland's north-east coast into a borrowed pickle jar and drove it to an office in Norfolk. There, it was tipped into an ashtray, sniffed, and set alight. That improvised ceremony marked the beginning of something far larger than anyone in the room could have calculated: a resource that would, within a decade, be described by Prime Minister Jim Callaghan as "God's best opportunity for Britain in 100 years." Output peaked around the turn of the millennium at 4.

4 million barrels of oil equivalent per day. Aberdeen, selected over Dundee precisely because its workforce had fewer ties to trade unions, became one of Europe's most prosperous mid-sized cities almost overnight. At its height, North Sea revenue approached 10% of the UK's entire tax take, underwriting Margaret Thatcher's programme of privatisation and cuts. Ewan Gibbs, an energy historian at the University of Glasgow, argues that the basin became entangled with something deeper than economics.

"At its peak, oil was associated not only with immense wealth but also with power and international prestige," he said. "It came to embody a sense of national renewal." That sense has now drained away alongside the reserves. Economically viable extraction has fallen sharply over two decades, and projections suggest that by 2030 the basin will produce only 15% of what it once delivered at its height.

BP, which had operated in the North Sea for six decades, announced this summer that it was leaving entirely — the latest and most emblematic of the major corporations to go. The jobs that offshore work once provided, often well-paid and plentiful, are disappearing with them.