A key adviser to Margaret Thatcher described Scotland and its people as pampered and a juicy target for public spending cuts in 1986, previously secret official files show.

David Willetts advised the Iron Lady that the Conservatives could win more votes in England if she was seen to be hammering the Scots.

Herald View: No more talk of snouts in the trough 

Now a peer who served as a science minister in David Cameron’s government, Lord Willetts has recently defended the millions of pounds spent on the UK's involvement in manned space missions.

His comments are revealed in private cabinet papers released for the first time under the 30-year rule. Past papers have showed he had said the Scots had their "snouts in the trough" of public spending.

The SNP said that people would not be "surprised at secret Tory plots to slash Scotland's budget" revealed in the newly released papers.

They also reveal how then Scottish Secretary Lord Younger even accused parts of his own government of being “prejudiced” against Scotland.

Colleagues were concerned that Lord Younger would resign amid the row.

In January 1986, Lord Willetts wrote a letter to Mrs Thatcher describing Scotland as the “only juicy” target left over from a previous round of public spending cuts.

He admitted that slashing the amount of cash given to Scotland could rebound disastrously on the Conservative party north of the Border.

However, he cited a poll in The Herald which suggested the party’s position was already perhaps “so bad that it might not deteriorate any further”.

“The envious North of England might even welcome an attack on the pampered Scots over the Border,” he added.

In the same letter he warned that Sir George was “very emotional” over the issue and “could even threaten to resign”.

He suggested to the Prime Minister that she use the "threat” of a study into public finances across the UK, which many Tory MPs believed would recommend a large drop in the Scottish budget, to force Lord Younger to agree to tens of millions of pounds worth of cuts.

Lord Younger was replaced in a cabinet reshuffle on January 11 1986 by Malcolm Rifkind .

The new Scottish Secretary came out fighting in February in a letter warning of the worsening state of the economy north of the Border and threats to Ravenscraig which later shut.

Meanwhile, the Treasury was arguing for cuts to the Barnett Formula, which determines how much money is given to Scotland, when UK ministers announced extra public spending south of the Border.

When the Cabinet met to discuss the issue on February 20, 1986, ministers faced accusations they were influenced by “resentment” against Scotland.

Mrs Thatcher ordered a limited study, but its results were inconclusive.

Officials warned that a full UK-wide needs-based review was required to determine whether or not the formula was fair.

In May, however, Lord Willetts reluctantly advised against one, but told the Prime Minister the threat of a review could be used to squeeze concessions from the Scotland Office.

On May 22 1986 Mrs Thatcher asked Edinburgh to draw up plans for population-based cuts after a document revealed falls in the numbers of people living north of the Border.

An SNP spokesman said: "No one will be surprised at secret Tory plots to slash Scotland's budget - the Tory austerity agenda is one of choice not necessity and it has been going on for decades. They are doing the same under Cameron."