CAMPAIGNERS are set to seek advice on a possible legal challenge to King Charles’s efforts to remain immune from prosecution under a Welsh law.

A report by The Guardian told how a Buckingham Palace official phoned the Welsh Government to seek assurances the monarch would not be prosecuted under the Agriculture (Wales) Act.

The elected minister who draw up the legislation agreed to a special exemption for the King last year but was reportedly “not happy” about it.

The King was exempted from regulations relating to the marketing of agricultural products, the disposal of carcasses and the disclosure of information to the Welsh state.

According to documents, on June 1 last year the Welsh Government noted in an internal memo that its lawyers “had been contacted by Buckingham Palace officials who have sought an assurance that Welsh ministers will take into account conventions regarding prosecuting the crown when making regulations under this bill”.

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In an email the following day, Welsh officials noted that Mick Antoniw, the Welsh government’s counsel general was “not happy with the exclusion” but “recognises the ongoing convention and therefore” agreed to it.

This was a reference to an ill-defined convention under which criminal and civil proceedings cannot be brought against the monarch as head of state.

Now anti-monarchy group Republic has said it will be seeking advice on a possible legal challenge to the monarch's immunity.

CEO Graham Smith said the convention “must be tested in court”.

He said: "Either we are all equal in law or none of us are.

"It is an outrage that Charles continues to exploit this outdated convention to ensure he's immune from prosecution.

"Charles should be ashamed of himself for demanding unique protections that allow him to bypass legislation farmers, rural communities and everyone else must abide by.

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"This convention must be tested in court, it cannot be right that a rule that dates back hundreds of years still protects Charles's private interests and wealth from the law of the land.

"I am seeking legal advice on whether it is possible to challenge this nonsense, and to ensure Charles and all the royals are held to the same standards as everyone else."

According to Buckingham Palace, the royal household rang the Welsh Government to ensure that “as a matter of legal correctness” the monarch could not be prosecuted under the Agriculture (Wales) Act.

A palace spokesperson said the convention had to be maintained as the draft act contained a particular type of legislation that would not rule out the possibility of a prosecution.