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Douglas Fraser, the BBC's Business/economy editor, Scotland has this analysis of the impact of the chancellor's measures on the Scottish oil industry.

He writes that a headline tax cut of a third - in the case of the Supplementary Charge on newer fields - "looks unusually generous in the current fiscal climate".

But he goes on: "It looks less generous when it's added to corporation tax, which runs at 30% of profits while other industries pay 20%. And it's less generous still, when you recall that the cut in supplementary charge from 30% to 20% precisely reverses the increase George Osborne announced in his 2011 Budget - to oil industry consternation.

"This was a Budget which spelled the end to the 40-year era of oil and gas being a government cash cow."