DID North Sea oil save Britain from disaster? Or was it a resource wrongfully plundered and pillaged 30 years ago?
How easily we have forgotten how near to meltdown the British economy has been in our lifetimes. Not the ERM crisis of September 1992 that did for the Major government; this was a blip compared with the crisis of 1975 that did for the Labour government of the time.
Cabinet papers released last week under the 30-year rule reveal two haunting truths about this period. The first is how near we came to a serious financial meltdown. The second is the acute sensitivity to the SNP challenge and the implications that it carried for the control of the North Sea oilfields. For it was this asset that was, in the words of a 1975 Foreign Office memo, a "rainbow spanning the sombre horizon". It was nothing less than the lifeline that led Britain, helped by an emergency IMF loan the following year, to eventual stability and prosperity.
It is easy now for pundits to wax eloquent on the "squandered national resource".
But options that now appear attractive in retrospect were just not available in 1975. This was not just a cyclical downturn year; it was Year Zero for Britain. This was the year in which inflation hit 25% and the UK stock market plunged to a despairing low, having fallen 73% from its post-war peak just three years earlier.
Notes on the economy handed in December 1974 to Prime Minister Harold Wilson by the economist Lord Balogh, the energy minister, revealed the extent of the concern. Balogh said the continuing balance of payments deficit could provoke "a violent withdrawal" of short-term money if people took fright.
He also warned of the risk of a "possible wholesale domestic liquidation starting with a notable bankruptcy... The magnitude of this threat is quite incalculable."
Balogh's scary prognostication was to prove spectacularly near the mark as the New Year dawned. On the first trading day of the New Year on the London Stock Exchange, shares in Burmah Oil were suspended. The company was forced to call for government assistance to help service its huge US loans.
The critical importance of North Sea oil, not just to the longer term future of the UK economy but the immediate buttressing of financial confidence, both here and overseas, became vividly clear when Burmah was made to hand over 51% of its North Sea operations, its 21.6% holding in BP, together with its 2% interest in Shell.
The Cabinet papers show that Chancellor Denis Healey wanted to stick to existing strategy, but was seeking to make it more effective.
Tony Benn, on the other hand, pressed for a far left programme involving import quotas, high tariffs, an element of rationing and deeper cuts in defence spending.
Wilson rejected Benn's stance and Healey went on to request a 2.3bn bail-out from the IMF.
The prospect of North Sea oil rescuing Britain from a balance of payments meltdown while pouring desperately needed tax revenues into the bare cupboard of the Healey Treasury played a key role in helping the economy through this appalling period.
The Cabinet papers released last week also reveal a Foreign Office assessment that Scotland would have a legitimate claim to 80% of North Sea oil. It said the union's future "was by no means secure" and that devolution should be used to buy off calls for independence.
It now looks as if the economic case for Scottish independence was then accepted in government, but by far the bigger priority for ministers at the time was the scale and severity of the economic crisis. Tax revenues from North Sea oil production were seen as integral to saving the economy.
Would an independent Scotland have done better with North Sea oil? A slower rate of depletion could well have helped create a huge Norway-style fund. But there are big challenges to this counter-factual, even assuming the 80% apportionment was legally upheld.
First, would the oil companies have gone along with slower extraction? After all, they had sunk enormous capital into North Sea exploration and development, much of it borrowed in expectation of near-term payback. Second, would the North Sea oil revenue (now 4.3bn) under this alternative model now be yielding more than the 11.3bn subsidy currently paid to Scotland?
Not least of all, how would the UK economy have fared in the meantime? Without North Sea oil it may well have succumbed to Balogh's prediction. Let's recall the exact words: a "wholesale domestic liquidation".