ALEX Salmond signed himself as Prince Charles’ “most humble and obedient servant” until deciding the traditional form of words was inappropriate in a democracy.

Mr Salmond last used the sign off in June 2009, two years after becoming First Minister.

The change of heart emerged after the details of seven personal letters between the two men were obtained by the Sunday Herald under the Freedom of Information (FoI) Act.

The cache of “black spider memos”, so named because of Charles’s handwriting, reveal the heir to the throne’s secret attempts between 2007 and 2010 to influence Scottish Government spending.

They show that Prince Charles privately lobbied Mr Salmond to give money and support to an organic food group, a stately home and the Prince’s own north highland food brand.

Mr Salmond backed the release of the letters amid opposition from the Prince.

Labour MSP Neil Findlay said that they showed Mr Salmond as “a bit of a sook” to royalty.

One extract from a letter, dated June 15, 2009, shows that Charles urged Mr Salmond to help the Soil Association in Scotland, of which the Prince is patron.

“I wondered if it might be possible to investigate whether there could be some form of support to assist the Soil Association in avoiding having to cut back their capacity for this initiative?” he wrote.

In reply Salmond said that Scottish ministers were already giving the association £148,563.

But, he said: “I have asked my officials to meet with Soil Association Scotland and discuss scope for further support in respect of opportunities identified in Your Royal Highness’s letter.”

He signed off: “I have the honour to be, Sir, Your Royal Highness’s most humble and obedient servant.”

Mr Salmond said that was the last time he had used that form of words because he decided that it was “inappropriate to a democratic age”.

Another letter asked Mr Salmond to appoint experts to help Charles’ north highland food brand, Mey Selections.

“Heartfelt thanks” was also expressed for the Scottish Government’s donation of £5 million towards the purchase of the stately home Dumfries House in East Ayrshire.

Republic, the anti-monarchy campaign group, called for all the prince’s letters to be published.

Mr Salmond said the prince, known as the Duke of Rothesay in Scotland, had not involved himself in party politics but raised legitimate matters of public interest.

A spokeswoman for Prince Charles said: “The Duke of Rothesay cares deeply about the United Kingdom, and tries to use his unique position to help others.”