It is an arcane parliamentary manoeuvre, rarely used for two centuries – although Labour invoked it last November to force the Government to publish what it hoped might be embarrassing studies on the outcome of Brexit.
But the party’s leader, Jeremy Corbyn, was on the other side of the procedure yesterday, as the Prince of Wales welcomed a delegation of MPs and peers to mark his 70th birthday.
Mr Corbyn and Theresa May were among the cross-party group who arrived at Clarence House to deliver a portfolio containing a humble address from each of the Houses of Parliament.
A book of rules published in the 19th century established the protocol as an appeal from parliament to the head of state that would be more binding than a simple opposition motion to a government who could simply ignore it.
The humble address contained in yesterday’s portfolio said little more than Happy Birthday, but it was the icing on the cake for heir to the throne.
The delegation from the Commons also included the Speaker, John Bercow, and the Liberal Democrat leader. Their address offered Charles “the warmest good wishes of the House upon the occasion of his 70th birthday, expressing the gratitude of the nation for his lifetime of service to the country and the Commonwealth and praying that His Royal Highness may long continue in health and happiness”.
Back at Westminster, MPs were given the opportunity to debate the message and add their own tributes. Mrs May praised Charles’ “total” commitment to public service, noting that he had spent his life “defying expectations and refusing to be categorised”.
She told MPs that his sons, the Duke of Cambridge and Duke of Sussex, were a “true credit to their father”.
The PM said Charles was often seen to be “a man ahead of his time”, citing his warnings on pollution, sustainable agriculture and the dehumanising effects of technology in the workplace.
Mrs May, whose own attempt at dancing on stage at her party conference this year, received mixed notices, also spoke of Charles’s love of music. “He remarked in 1974 that ‘if I hear rhythmic music, I just want to get up and dance’ – something I’m sure many of us empathise with,” she said.
Mr Corbyn, who is known for his republican beliefs, praised Charles’s “commitment” to public service and charity, and his “passion” for notable causes.
“It might come as a surprise to many that His Royal Highness and I have something in common,” he said. “We’re both, it seems, leaving it late when it comes to career progression, although he has had a lifetime preparing for this role.”
He also suggested giving Charles a jar of “Corbyn Original jam” from his allotment, but worried: “Will my jam match up to the standard of Prince’s Duchy Original jam? I don’t know.”