Prince Charles
27 letters by Prince Charles have been publishedGetty

The secret letters of Prince Charles have finally been published following a decade-long campaign by the Guardian newspaper. The Supreme Court ruled it was in the public interest to publish the Prince's 27 letters, which he sent to the previous Labour government between 2004 and 2005.

The so-called "black spider" memos are set to provide an insight into how the Prince went against constitutional law and used his royal position to lobby the government over concerns closest to him, such as agriculture and the environment.

But it seems so far that the Prince's correspondence between ministers has not revealed anything too controversial - subjects ranged from the mundane topic of beef farming to the highly politicised issue of informing former Prime Minister Tony Blair that he believed the armed forces were under resourced.

A Clarence House spokesman said: "The publication of private letters can only inhibit his ability to express the concerns and suggestions which have been put to him in the course of his travels and meetings.

"This view has been given effect by Parliament, which passed legislation in 2010 to ensure that the communications of The Prince of Wales, and that of The Queen, should be exempt from publication under the Freedom of Information Act. This change emphasised the unique constitutional positions of the Sovereign and the Heir to the Throne. Clarence House continues to believe in the principle of privacy."

The campaign to see the letters was led by Guardian reporter Rob Evans using the Freedom of Information Act.

In his column today Evans heralded the letters' publication as a triumph for the Act - despite costing at least £274,000 in legal fees to achieve it.

Prime Minister David Cameron did his best to veto the disclosure but was overruled by the Court of Appeal last year which deemed such efforts as "unlawful", which was later upheld by the Supreme Court.

For the full list of the Prince's correspondence visit gov.co.uk