3. The UK Government "underplayed the value of the oil to the country".
Denis Healey: Westminster 'worried stiff' about losing North Sea oil
"I think we (England) would suffer enormously if the income from Scottish oil stopped but if the Scots want it, they should have it and we would just need to adjust.
North Sea oil output to rise by a third over five years - The Independent
In 1974, Professor Gavin McCrone was asked by Edward Heath's Conservative government to work out the value of Scotland's oil.
The government kept the report secret.
Lord Healey, now 95, told Holyrood magazine: "I think we did underplay the value of the oil to the country because of the threat of nationalism but that was mainly down to Thatcher.
"We didn't actually see the rewards from oil in my period in office because we were investing in the infrastructure rather than getting the returns and, really, Thatcher wouldn't have been able to carry out any of her policies without that additional five per cent on GDP from oil.
British North Sea oil output seen at 1977 levels this year | Reuters
About half the oil is still to come.
The Scottish Government's inaugural Oil and Gas Analytical Bulletin in March 2013 has a post-independence scenario which could see "oil and gas production in Scottish waters generating £57bn in tax revenue between 2012-13 and 2017-18".