Hundreds of Privy Counsellors have been shut out of the Prince of Wales’ accession, amid complaints the ancient body of monarch’s advisers is being relegated to a “Disneyland showpiece”.

       A row has broken out after a letter was sent to all Privy Counsellors, who act as the Queen’s official advisers, informing them that attendance at the Accession Council - convened within 24 hours of the death of a sovereign - has been significantly scaled back.

       Held at St James’s Palace, the Accession Council traditionally takes place before Parliament meets. It is the first official event the Prince of Wales will attend as King when the time comes.

       Following a review, only 200 of more than 700 Privy Counsellors will now be able to attend. Priority will be given to former Prime Ministers, Cabinet and shadow cabinet ministers, the Archbishops of Canterbury and York, party leaders and the leaders of devolved nations, as well as representatives of the senior judiciary.

       Those who fail to make the initial cut are being asked to enter an annual ballot for one of the remaining seats.

       The change has been authorised by Downing Street and Mark Spencer, Leader of the House of Commons, who also acts as Lord President of the Council.

       It follows reports that successive prime ministers have used appointments to the Privy Council as a “shameless form of patronage”, prompting its numbers to more than triple during the Queen’s reign.

       Current members include Jeremy Corbyn, the former Labour leader, Diane Abbott, the former shadow home secretary, and John Bercow, the former speaker of the House of Commons. Sir Nick Clegg, the former leader of the Liberal Democrats who now works for Facebook, is also a Privy Counsellor, along with disgraced MPs Keith Vaz and Owen Paterson.

       'No option but to reduce number of attendees'

       In a letter seen by The Telegraph, Richard Tilbrook, Clerk of the Privy Council, wrote: “With the agreement of Number 10 and the Lord President of the Council, we have advised the Royal Household that - for strong safety and operational reasons - there is no option but to reduce the number of attendees to 200 if we are to deliver the first high profile event of the King’s reign to the high presentational and safety standards required of the occasion.

       “The historic nature of St James’s Palace presents a number of significant challenges in terms of capacity, accessibility and crowd flow.

       “The pace at which an Accession Council must take place limits significantly the additional security, infrastructure and provision we are able to make on the day.

       “Taken together, these issues posed a considerable risk to the dignified delivery of an Accession Council. Even with a number of mitigations in place, there was a significant risk of overcrowding and lengthy queuing, resulting in safety issues and a compromised experience for attendees, and potentially delaying the start of the Accession Council.

       “The revised attendee list will now comprise Privy Counsellors selected on an ex-officio basis, a small number of Privy Counsellors selected via an annual ballot, and certain other dignitaries.”

       The number of Privy Counsellors has swelled from 175 when the Queen took the throne in 1952 to more than 700 today.

       Sir Edward Leigh, the Tory MP for Gainsborough, who was appointed to the Privy Council three years ago, said the proposal “risks reducing the Privy Council into a mere Disneyland showpiece, rather than a body that is central to the constitutional functioning of the United Kingdom”.

       In a reply to Mr Tilbrook, seen by the Telegraph, he questioned why Privy Counsellors were not consulted on the plan - which he argued “is a deliberate and unnecessary move that subverts the very nature of Her Majesty's Most Honourable Privy Council.”

       Suggesting that the Accession Council could be moved to Westminster Hall or Buckingham Palace, where there is more space, he added: “I must also object to the proposal to have an annual ballot open to all Privy Counsellors not on the 'ex-officio' list.

       “This proposal is illogical. It would mean that a Privy Counsellor who finds him or herself in Orkney, the West Indies, or Papua New Guinea on the day in question might have a place guaranteed via the ballot but be unable to use it, while a Privy Counsellor in London who is ready, willing and able to attend would, it would seem from your suggestion, be prevented from doing so.”

       Copies of his letter have been sent to the Prime Minister and the Prince of Wales’ principal private secretary.

       Founded in 1708, the Privy Council formally advises the sovereign on the exercise of the Royal Prerogative. As a body corporate (as Queen-in-Council), it issues executive instruments known as Orders in Council, which among other powers enact Acts of Parliament. Members are entitled to be styled "the Right Honourable”.

       Queen Victoria insisted that there should be no lavish promotions to her Privy Council, while her grandson, George V, said appointment to the prestigious body was “a greater honour than a peerage”. Some of Sir Winston Churchill’s nominations were resisted by George VI, but the Queen's non-partisanship has seen the numbers swell since the Coronation.

       Critics remarked on the “coincidence” of Sir Edward, a staunch Brexiteer, announcing he would back Theresa May’s withdrawal agreement just two weeks after the former Prime Minister appointed him to the Privy Council in 2019.