Prince Charles exploited a controversial procedure to compel government ministers to secretly change a proposed law to benefit his landed estate, according to documents uncovered by the Guardian. Official papers unearthed in the National Archives reveal ministers in John Major’s government yielded to his demands amid fears that resisting the heir to the throne could spark a constitutional crisis. Ministers backed down to “avoid a major row” with the prince, effectively allowing him to force the hand of the elected government. The disclosure of the documents provides further evidence of how the royal family has used the secretive procedure known as Queen’s consent to alter legislation to benefit their private interests. Under the procedure, the monarch and her eldest son are given copies of draft laws in advance so they can examine whether the legislation affects their public powers or private assets, such as his Duchy of Cornwall estate or the privately owned estate at Sandringham. Ministers must obtain the consent of the Queen and the prince before relevant legislation can be approved by parliament. This procedure is different than the better known procedure of royal assent, a formality that makes a bill become law. A Guardian investigation has revealed that the Queen’s consent procedure has been used by the monarch in recent decades to privately lobby for changes. During her reign, ministers have been required to secure approval from the Queen or her son for more than 1,000 parliamentary acts before they were implemented. Buckingham Palace and the government say Queen’s consent is a “purely formal” part of the parliamentary process and is granted by the monarch as a matter of course. The palace has said that “consent is always granted by the monarch where requested by government” and that “this process does not change the nature of any such bill”. But the newly revealed documents, concerning a leasehold reform act that became law in 1993, provide detailed evidence of Charles applying pressure on elected ministers to ensure an exemption to prevent his own tenants from having the right to buy their own homes. The Windsor family has used the consent procedure to vet at least four draft acts that have changed leasehold laws since the 1960s. Under such laws tenants live in properties for a specific number of years on a lease, instead of owning it outright. The changes have given tenants across the country the legal power in certain circumstances to buy their homes from their landlords. Letters and internal memos from September and October 1992 show Charles took a “close personal interest” in Newton St Loe, a small Somerset village that is part of the £1bn Duchy of Cornwall estate, and insisted his properties there should be excluded from the proposed bill. His lobbying secured a special exemption for the village that has to this day left the tenants financially worse off. The documents also reveal Charles wrote directly to Major in October 1992 noting that he would be shortly receiving a request to give his consent to the leasehold bill, and expressing his “particular concern” about another aspect of the proposed law – which he feared would permit tenants to buy and redevelop historic properties without preserving their “special character”. ‘It is important to avoid a major row with the Prince of Wales’ Charles, as the heir to the throne, is given a private annual income – currently about £20m – out of the profits made by the Duchy of Cornwall, a property estate. The 52,000-hectare estate collects rents on properties across 20 counties in England and Wales. However, in some areas its tenants are barred from buying their homes. These tenants, whose number is unknown, continue to pay rent to the duchy – money that in turn is paid to the prince. Last year, after a Guardian investigation revealed the Windsors had vetted several leasehold reform acts, the duchy said in a statement that neither it nor the prince had had “any involvement in the drafting of legislation that relates to any part of leasehold reform”, including the question of tenants buying their own homes. In September 1992, lawyers representing the duchy privately told the government they were concerned about the proposals contained in a new leasehold bill, and argued the Newton St Loe tenants should be denied the right to buy their homes. David Landale, the duchy’s secretary, said the village – one of the duchy’s main holdings – was “particularly well liked and valued by His Royal Highness because of its well-balanced mixture of farms and woodland”. On 30 September a Whitehall official, JE Roberts, warned ministers that “the difficulty is that the Prince of Wales takes a close personal interest in the development of this village”, adding that Charles saw “no reason why he should now relinquish control. It has been made clear to me that if the government wish to press ahead on this issue, the prince will wish to discuss it at the highest levels.” Roberts stressed: “The Prince of Wales is likely to come back on Newton St Loe. Ministers will then need to decide whether it is worth fighting him on the issue.” Sir George Young, the housing minister at the time, and another minister, Tony Baldry, believed it was not justified to prevent the Newton St Loe tenants from buying their homes when others in the country had that right, according to a letter. It was feared it would create a precedent for other major landowners. In a memo on 9 October, Roberts noted: “No special case can be made beyond the fact that the prince has taken a special interest.” He cautioned that ministers’ most important objective was to “ensure that the consent of the Queen and the Prince of Wales to the bill is obtained … their consent is necessary before the bill may be introduced.” “Ultimately I assume that the will of ministers can prevail over that of monarchy but a constitutional crisis would add a further dimension of controversy to the bill which would be better avoided,” he wrote. Roberts warned the ministers faced a choice between either conceding to the prince or staying firm and “looking for a mechanism to break the deadlock. Unfortunately I am not aware that our constitution has provided any such mechanism!” On 22 October, Roberts advised: “On the basis that it is important to avoid a major row with the Prince of Wales … there is a case for letting matters rest … It is open to the minister to fight if he wishes, recognising that this is likely to have costs on both sides.” However, Baldry replied: “We have probably got as far as we can with this … we should let the matter rest.” Young agreed: “I could live with this – reluctantly.” On the same day, the prince gave his consent to the bill. The special exemption barring the Newton St Loe tenants from buying their homes was made public only during the enactment of a later leasehold act in 2002. A duchy spokesperson said: “The Duchy of Cornwall estate is exempt from leasehold reform legislation but has agreed to act as if bound in, apart from in a very small number of specifically identified areas including Newton St Loe. As you can imagine, we do not discuss individual leaseholds.” In practical terms only a small number of Newton St Loe tenants are affected by the ban. But they say they have suffered bitter financial hardship as a result of the prince’s special rights. One, Jane Giddins, said she and her husband cannot borrow against their home to pay for social care for themselves in the future. She added that the value of the 99-year-old lease on their home – their main asset – diminished steadily as it got closer to ending. “It is total injustice, and feudal,” Giddins said. “Because my freehold is owned by someone who is immensely wealthy and powerful, I am not protected by the law that applies to everyone else in this country. I can’t do anything about it.” She said that when she and her husband took the lease in 1996, the duchy told them about the ban on buying it – but she could not have known that the prince had lobbied to keep the village exempt from leasehold reform. “I took the view that it was so obviously anachronistic and grossly unfair, that by the time I needed to sort it out, the law would have been changed. And I had no idea that the duchy would be able to stop the law being tidied up.”