Prince Charles may be preparing the ground to become a more outspoken and controversial monarch than his mother as the House of Windsor gets its “gentle succession” under way, constitutional experts said yesterday.

The heir to the throne is expected to take on more of the 87-year-old Queen’s duties, including overseas visits, as part of a slow convergence of their roles which this weekend saw the announcement of the merger of their press offices into a single “seamless” operation.

The move was accompanied by briefings that Charles would be expected to do “less of his campaigning” as he increasingly stands in for the head of state at official events and prepares to assume the mantle of monarch.

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But royal sources yesterday held out the prospect of a different approach by underlining that the Queen and her eldest son were from “very different eras” and leading constitutional experts pointed out that the prince is under no obligation to follow his mother’s example in studiously avoiding expressing controversial opinions throughout her near 62 years on the throne.

Modern British monarchs have habitually adopted a position of political neutrality because of their constitutional power to call for the formation of a government. The present queen has gone further and stayed out of public debate on nearly every topic.

Colin Talbot, professor of government at Manchester University said: “This is a constitutional convention which can be changed by the simple fact of a monarch doing things differently. There is nothing written down which says the monarch cannot express opinions. Charles could quite simply be a more outspoken monarch.

“We have got very used to Elizabeth II saying nothing controversial but having a monarch who stays quiet on such matters is a very post-1945 phenomenon. Her predecessors certainly were more prepared to express opinions. It may also be difficult for Charles to stop behaving as he is used to.”

Indeed, on subjects from the superiority of neoclassical architecture over anything newfangled fashioned from glass and steel to the efficacy of homeopathy, the 65-year-old prince is famously not backwards about coming forward with his views on the issues he holds dear.

His attempts to influence the Qatari royal family over the £1bn redevelopment of a former barracks in London’s Chelsea ended with a High Court judge describing his intervention as “unexpected and unwelcome”.

A collection of his letters to ministers, dubbed the “black spider memos” in Whitehall owing to the princes’ expansive handwriting, are the subject of an eight-year High Court battle to force their disclosure after the Government invoked a rarely-used veto on the grounds that their publication could damage the perception of his political neutrality.

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Ministers have conceded that the 27 letters contain the “most deeply held personal views and beliefs” of the prince, who enjoys the right to consult with the government of the day in preparation for his eventual accession to the throne but cannot seek to exert influence on political decisions.

Clarence House declined to comment on whether the emerging “job share” between the Queen and the Prince of Wales would be accompanied by a decline in use of the royal soap box. A source pointed out Charles’s work with numerous charities and interest in issues from rural life to urban blight, adding: “He and the Queen are obviously different people and they have had different experiences.”

The prospect of an activist monarch turning Buckingham Palace into a royal think tank with an eclectic agenda and a direct line to Downing Street nonetheless remains remote. But there is a growing expectation that the reticence of the New Elizabethan era may come to an abrupt end with the advent of King Charles III.

James Hallwood, associate director of the Constitution Society, which campaigns for better-informed debate about constitutional reform, said: “What I suspect might be the case, is that Prince Charles will be encouraged to make any statements broader. The Queen speaks openly on her Christian faith and on the Commonwealth without any controversy. Perhaps Charles will look at the environment as a broad issue rather than dealing with specifics.”

Even as he prepares to adopt a more regal profile, there is little sign of Charles abandoning his favourite topics. The prince has reportedly raised concerns in recent weeks with the Health Secretary Jeremy Hunt over delays in the establishment of an official register of alternative medicine practitioners.

It is understood that the prince’s new role will not extend into the routine Government consultation or the weekly private meetings between the monarch and the prime ministers, which will remain the domain of the Queen.

But campaigners said the blurring of the distinction between monarch and heir raises important concerns about the relationship between royalty and the Executive.

Graham Smith, chief executive of anti-monarchy group Republic, said: “There should not be a succession by stealth. If that is happening, then very obvious questions arise about the level of access to ministers that Charles enjoys and the influence he is having on policy.

“There is a reason that the Queen has stayed out of politics and that is because if she was to become involved it would put the whole institution of the royal family at risk. The public would have little or no truck with a political monarch.”

In the meantime, it remains to be seen whether Charles will see his incremental progress to the throne as a fair deal for courting less controversy.

Dr Andrew Blick, a lecturer at the Centre for Constitutional Studies at Kings College London, said: “That might be the expectation. How it will work out in practice, which rests on self-restraint, remains to be seen.”