Jeremy Corbyn has turned down an offer to be inducted into the privy council in person by the Queen.
The Labour leader’s office said he was unable to attend the service due to prior "private engagements".
The ritual of induction to the Privy Council, traditionally a group of a monarch’s most-trusted advisers, involves kneeling before the Queen and kissing her hand.
The Leader of the Opposition is typically appointed to the Privy Council so they can receive secret briefings from the security services.
Mr Corbyn could avoid meeting the Queen altogether using a mechanism called an Order in Council which means the Privy Council can appoint a member who is not there - this is typically used for members who are abroad.
One Privy Council member told the Telegraph: "Firstly it is deeply insulting and secondly it is not grown up – not to go to see the monarch is just extraordinary.
"I am sure that what they would have done is not make him kneel. But what this really means is that he is not prepared to put himself in the position of a serious leader who can be trusted."
David Cameron called Mr Corbyn to invite him to join the ancient order when he was elected as Leader of the Opposition on 12th September.
A spokesman for Mr Corbyn said "Jeremy was invited but couldn't make it due to private engagements."
He said they were "unsure" about the protocol of bypassing the oath and no alternative date had been set for the ceremony to take place.
According to the Guardian, the council, which has around 600 members and dates back to Norman times, rarely meets and does not discuss serious business.
Additional reporting by PA
