The "black spider" memos are letters and memorandums written by Charles III of the United Kingdom, during his tenure as Prince of Wales, to British government ministers and politicians over several years. As the modern British monarch remains politically neutral by convention, the letters were controversial because of Charles' then-position as eldest child of the British monarch Queen Elizabeth II and heir apparent to the British throne.

The letters were sent by Charles in a private capacity, but concerns have been raised that they may represent the exercise of undue influence over British government ministers. Issues about which Charles has expressed public views include farming, genetic modification, global warming, social deprivation, planning and architecture. This led the press to label Charles as a "meddling prince". The content of the "black spider" letters, named after Charles' distinctive handwriting, was known only anecdotally and from memoirs and leaks, until 13 May 2015 when the Information Tribunal ordered the release of most of the correspondence.

These events were set in motion in 2010, when The Guardian journalist Rob Evans made an application under British Freedom of Information legislation to see the Prince's 2004 and 2005 letters to ministers. After several legal cases the application was eventually refused by the Attorney General Dominic Grieve in October 2012, and the case was the subject of an appeal in the Supreme Court which, in March 2015, ruled against the government's decision, and allowed for the later publication of the letters.

Upon their release, the memos were variously described in the press as "underwhelming" and "harmless", and The Daily Telegraph claimed that their release had "backfired on those who seek to belittle him".

Background Charles' letters are written by hand before being sent to be typed up. After the letters are returned to Charles to sign, he often adds additional comments in flowing black or red ink across the page using underlining and exclamation marks. It is these additions and his distinctive spidery handwriting that have given his letters their nickname.

Charles has written to ministers on the understanding that his remarks are private.

Letters to ministers have also been sent from the Prince's charities, foundations and campaign groups. These letters have been described as "advocacy correspondence", written by the Prince to advance the work of his charities or in an attempt to promote his views.

The principal private secretary to the Prince of Wales, Sir Michael Peat, said in 2007 that the Prince "...is always very careful to ensure he is not politically contentious or party political, and as far as I am aware even his most ardent critic has never suggested he is."

The "dissident" prince In 2006, the former deputy private secretary and press adviser to the Prince of Wales, Mark Bolland, said that the Prince had referred to himself as a "dissident" who worked against the prevailing political consensus. Concerning Charles's views, Bolland said that he "...routinely meddled in political issues and wrote sometimes in extreme terms to ministers, MP's and others in positions of political power and influence...The prince used all the means of communication at his disposal, including meetings with ministers and others, speeches and correspondence with leaders in all walks of life and politicians. He was never party-political, but to argue that he was not political was difficult...These letters were not merely routine and non-controversial...but written at times in extreme terms...containing his views on political matters and individual politicians at home and abroad and on international issues...I remember on many occasions seeing in these day files letters which, for example, denounced the elected leaders of other countries in extreme terms, and other such highly politically sensitive correspondence."

In 2009, a spokesperson for the Prince said that his role as a privy counsellor gave him the right to communicate confidentially with ministers on matters that concern him, adding that communication between the Prince and ministers should be treated as private and confidential on all sides. In 2002, the Prince's office issued a statement defending his right to privately correspond with government ministers. The 2002 statement said that the Prince "...takes an active interest in all aspects of British life and believes that as well as celebrating success, part of his role must be to highlight problems and represent views in danger of not being heard...this role can only be fulfilled properly if complete confidentiality is maintained...It is proper and right that he should take an interest in British life. It is not about exerting undue pressure or campaigning privately."

In 2008, the Prince's friend and biographer, Jonathan Dimbleby, said that royal aides had informally started to consider redefining the role of the monarch to allow a future King Charles "...to speak out on matters of national and international importance in ways that at the moment would be unthinkable".

The 'Cumbrian farmer letter' and letters to Blair and Irvine A letter from Charles to the then Prime Minister Tony Blair was leaked on the day of the Countryside Alliance's 'Liberty and Livelihood' protest march in September 2002. In the letter, Charles associated himself with the views of a farmer from Cumbria, who, complaining of the British government's treatment of rural workers said that "If we, as a group, were black or gay we would not be victimised or picked on." Charles also wrote that if rural people were "any other minority" the government would make greater efforts to protect them. The government was also blamed for "destroying the countryside". Charles was believed to have written the letter in April 2002, and advisers were said to have attempted to persuade him not to send it, and suggested that Charles raise the issue with Blair when next they met. It was not known who "leaked" the letter, with speculation falling on a variety of sources including 10 Downing Street, the Labour Party, sources close to Charles's household, or the Conservative Member of Parliament Nicholas Soames. The allegation was denied by 10 Downing Street and Soames.

Charles wrote regularly to Blair and they would meet at least four times a year when Blair was Prime Minister. It was said that the Lord Chancellor, Lord Irvine, had complained "bitterly" about being "bombarded" by letters from Charles, but this was denied by Irvine. Letters to Irvine in June 2001 had complained about the Human Rights Act and were critical of the "degree to which our lives are becoming ruled by a truly absurd degree of politically correct interference". Charles also complained to Irvine that the United Kingdom was "sliding inexorably down the slope of ever increasing, petty-minded litigiousness" and wrote in 2002 about "ever-more prescriptive laws – for example, health and safety at work legislation, the blame culture...and the bureaucratic red tape which accompanies new rules".

Qatari letters, Chelsea Barracks scheme The Prince of Wales has occasionally written about architectural projects that utilise styles that he is aesthetically opposed to, such as modernism and functionalism. In 2009 the Prince wrote to the Qatari royal family, the developers of the Chelsea Barracks site in west London, labelling architect Richard Rogers's design for the site "unsuitable" and the plans "a gigantic experiment with the very soul of our capital city". Rogers was subsequently removed from the project and The Prince's Foundation for the Built Environment was appointed to propose an alternative. Rogers claimed the Prince had also intervened to block his designs for the Royal Opera House and Paternoster Square, and condemned Charles's actions as "an abuse of power" and "unconstitutional". Lord Foster, Zaha Hadid, Jacques Herzog, Jean Nouvel, Renzo Piano, and Frank Gehry, among others, wrote a letter to The Sunday Times complaining that the Prince's "private comments" and "behind-the-scenes lobbying" subverted the "open and democratic planning process". Piers Gough and other architects condemned Charles's views as "elitist" in a letter encouraging colleagues to boycott a speech given by the Prince to RIBA in 2009.

2004–05 letters: FOI campaign by The Guardian In 2010, Rob Evans, a journalist for The Guardian newspaper, applied under the Freedom of Information Act 2000 to see copies of correspondence between Charles and ministers in seven government departments. The government refused to grant the request. The ministerial recipients of the letters and the dates which they were received were also deemed to be secret by the government. The 27 letters concerned were written between September 2004 and April 2005. The Guardians challenge was the first of its kind to attempt to obtain royal correspondence.

Evans wished to see letters between Charles and the Department for Business, Innovation and Skills, the Department of Health, the Department for Children, the Department for Education, the Department for Environment, Food and Rural Affairs, the Department for Culture, Media and Sport, the Northern Ireland Office and the Cabinet Office.

2009: Further letters revealed, Prime Ministerial block on disclosure In addition to the letters sent in 2004 and 2005 sought by The Guardian, the same paper had revealed in 2009 that Charles had written directly to eight government ministers since 2006. The Department for Environment, Food and Rural Affairs, the Department for International Development, HM Treasury, the Foreign and Commonwealth Office, the Department for Work and Pensions, the Department for Education and Skills, the Department for Communities and Local Government, and the Department for Culture, Media and Sport all received personal letters from Charles between 2006 and 2009. The government refused to release the content of the letters sent between 2006 and 2009.

In addition to Charles's letters, his advisers had also written to five government departments and to members of the cabinet seeking to bring the government's policy into line with Charles's beliefs on matters such as the building of hospitals and ecotown design. Aides from the Charles's architectural charity had written to the then Secretary of State for Communities and Local Government, Hazel Blears, urging the government to adopt his positions on ecological design and planning. The Secretary of State for Health, Patricia Hewitt, also received letters from Charles's aides, who recommended the adoption by hospital trusts of design techniques devised by his architectural charity. The Chief Secretary to the Treasury, Andy Burnham, also received letters concerning the sustainable increase of the housing supply in a way "which provides support for the [prince's] Foundation's mission to promote timeless and ecological ways of planning, designing and building".

In December 2009, Prime Minister Gordon Brown ordered a block on the disclosure of correspondence sent to ministers by members of the royal family at the same time as the information commissioner, Christopher Graham, blocked the release of an earlier set of correspondence which involved Prime Minister Blair.

2010: Initial FOI appeal