The Prince of Wales tackled former prime minister Tony Blair over a lack of resources for the Armed Forces fighting in Iraq, previously secret letters have revealed.
Publication of correspondence between Charles and government ministers following a long-running legal battle revealed the Prince lobbied Mr Blair and other ministers on a range of issues from badgers and TB to herbal medicine, education and illegal fishing.
Twenty-seven letters - 10 from Charles to ministers, 14 by ministers and three letters between private secretaries - were released following a 10-year campaign by Guardian journalist Rob Evans to see the documents after a freedom of information request.
Charles is due to visit Liverpool today where he and the Duchess of Cornwall will carry out a number of engagements.
During a visit yesterday ahead of the publication of the letters one of the Prince's senior aides ripped the cover off Channel 4 journalist Michael Crick's microphone when he asked Charles if he was 'worried' about the documents being made public.
Among those corresponding with the Prince was former Welsh secretary Peter Hain, who said that because of his post and Charles's role as the Prince of Wales they wrote regularly, and he would send reports to Charles for him to comment on.
Mr Hain said: 'I'm not a monarchist but I think he was well within his rights to express his views. You have to be a weak minister to somehow be rolled over simply because you receive a letter from the heir to the throne.'
He added: 'I never had a problem with it; I thought his letters were interesting and passionately expressed. Often I agreed with him and sometimes I disagreed with him. I thought it was really healthy he was expressing his views.'
Margaret Beckett, who was environment secretary in the Blair administration during the period covered by the letters released, said she received correspondence from Charles 'every now and again'.
She said: 'I certainly had letters from the Prince but didn't have that many. All I can think of - and maybe we were fortunate in that respect - on the whole my department and the Prince were on the same page. On issues like foot-and-mouth and organic farming - all sorts of things.'
She said she was perfectly happy to have the input of Charles just as she would from anyone else, adding: 'I don't remember any of his letters being a problem.'
But Paul Flynn, Labour MP for Newport West, suggested Charles was putting the future of the royal family at risk through politically partial statements.
Charles is understood to be 'disappointed' that the confidentiality principle was not maintained as his memos - written between September 2004 and March 2005 - were finally published.
The Prince, who will one day as king be head of the Armed Forces, complained to Mr Blair about British forces in Iraq 'being asked to do an extremely challenging job without the necessary resources'.
In one detailed and lengthy letter to Mr Blair, dated September 8 2004, the Prince wrote of problems with deploying new Oxbow surveillance technology, which he described as a 'major advance' for the military.
But he warned the deployment of the equipment was 'being frustrated by the poor performance of the existing Lynx aircraft in high temperatures'.
Charles said: 'Despite this, the procurement of new aircraft to replace the Lynx (helicopter) is subject to further delays and uncertainty due to the significant pressure on the defence budget.
'I fear this is just one more example of where our Armed Forces are being asked to do an extremely challenging job (particularly in Iraq) without the necessary resources.'
In his response to the Lynx letter, Mr Blair replied on October 11 that year, saying that 'limitations of the existing platform' were well known by the MoD, and the budget for the coming years included investment in helicopters.
In the same note to Mr Blair, the Prince asked him to put 'pressure' on the Department for Environment, Food and Rural Affairs over the bureaucratic burdens facing farmers.
Charles wrote: 'Suffice it to say that any pressure which you can bring to bear on Defra through the Panel for Regulatory Accountability, which you told me you are chairing, would be much appreciated.'
In another letter to Mr Blair, the Prince described opponents of a badger cull as 'intellectually dishonest' and advocated culling to tackle tuberculosis in cattle.
Writing in February 2005, Charles criticised the 'badger lobby' for not minding about the slaughter of cattle which contract the disease but objecting to the killing of badgers.
He urged Mr Blair to 'look again at introducing a proper cull of badgers where it is necessary', warning that the rising number of cases of TB in cattle was the most pressing and urgent problem facing the agricultural sector.
'I, for one, cannot understand how the 'badger lobby' seem to mind not at all about the slaughter of thousands of expensive cattle, and yet object to a managed cull of an over-population of badgers - to me, this is intellectually dishonest,' he wrote.
The then Labour government resisted pressure to launch a cull although David Cameron's coalition government did go ahead with one on a limited basis in 2013.
As of March last year, more than a quarter of a million pounds (£274,481.16) had been spent by the Government on legal fees to try to block the publication of the letters.
The money was spent by eight government departments as former attorney general Dominic Grieve tried to prevent their release, claiming it would undermine the principle of the heir to the throne being politically neutral.
The real cost is likely to be much higher due to further legal wrangling since the figures were published.
Charles also described a European regulation to restrict practitioners of herbal medicine as like 'using a sledgehammer to crack a nut', and also complained to Mr Blair about regulatory body the Office of Fair Trading, describing it as a 'serious obstacle' for dairy co-operatives.
Other issues raised by the Prince included the plight of the albatross and the fate of the Patagonian toothfish.
There were no handwritten 'black spider' letters among the batch released - so-called because of the black ink used by the Prince in some correspondence and his habit of underlining words - and all were typed.
Both Mr Blair and the Prince signed their letters to one another 'Yours ever' and Charles often apologised for the length of his note which frequently ran to three or four pages of typed A4.
Charles even made a joke about the Freedom of Information Act - the very legislation which enabled the publication of his correspondence - in one of his notes to Mr Blair.
He said: 'It was very good to see you again the other day and, as usual, I much enjoyed the opportunity to talk about a number of issues.
'You kindly suggested that it would be helpful if I put them in writing - despite the Freedom of Information Act!'
Guardian editor-in-chief Alan Rusbridger described it as 'shocking' that the Government had wasted public money trying to prevent the publication of the letters.
'We fought this case because we believed - and the most senior judges in the country agreed - that the Royal Family should operate to the same degrees of transparency as anyone else trying to make their influence felt in public life,' he said.
Charles was at St James's Palace in central London when the letters were released, speaking at the Prince's Trust's Our Young People Our Future conference and joining a reception with guests including television presenters Ant and Dec, who are Trust ambassadors, and Channel 4 newsreader Jon Snow.
The Prince made no mention of the letters during his speech.
Clarence House defended the Prince's decision to write the letters, with a spokesman saying: '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.'
But his senior aide suggested the experience was unlikely to put him off raising matters that are brought to his attention in the future.
Charles's principal private secretary William Nye said: 'He will think about how he deals with things but I think he'll continue to want to reflect the views that he hears from members of the public, and talk about things that matter to our society and the world to ministers of any government.'
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