Jeremy Corbyn is to be sworn in as a member of the privy council on Wednesday, enabling him to receive confidential security briefings.
The Labour leader has confirmed that he intends to join the body, but has not said whether he will kneel on a footstool or kiss the Queen’s hand as part of the process.
New members are also meant to swear to defend the monarch against “all foreign princes, persons, prelates, states or potentates”.
As a member of the council, which is the oldest functioning legislative assembly in the UK, Corbyn will also have the right to use Right Honourable as a title.
Labour declined to give more details about how Corbyn will conduct the swearing-in ceremony. His choices may never be made public, because meetings of the organisation take place in private.
According to the Royal Encyclopaedia, the protocol is that: “The new privy counsellor or minister will extend his or her right hand, palm upwards, and, taking the Queen’s hand lightly, will kiss it with no more than a touch of the lips.”
The late former cabinet minister and leftwinger Tony Benn revealed in his diaries that he kissed his own thumb instead of the Queen’s hand.
Some Tory MPs and the Labour MP Simon Danczuk criticised Corbyn for missing the first meeting because of prior engagements.
Corbyn had previously indicated that he would have to think about whether to attend the Buckingham Palace ceremony at all, suggesting he could have tried to become a member through an order in council.
Since then, however, the Labour leader made clear he intends to be sworn in. The meeting, due to take place on Wednesday afternoon, is the second opportunity for him to attend.
The issue of Corbyn’s membership has been much discussed because he is a lifelong republican.
The council is made up of 600 senior figures including politicians, which tends not to transact any serious business. Not many of its members turn up to meetings, which happen roughly once a month.
Michael Foot and Neil Kinnock both became privy counsellors, which entitled them to higher-class security information and briefings.
Since becoming Labour leader, Corbyn has come under intense criticism from some sections of the media over his participation in ceremonial events.
His critics have variously attacked him for not bowing low enough at the cenotaph on Remembrance Sunday, appearing not to sing the national anthem at a service and “snubbing” the Rugby World Cup opening ceremony by turning down an invitation to attend.
