Why are MPs banned from clapping?
Britain's Parliament has some pretty bizarre rules - as the new intake of SNP MPs found out when they were given a stern warning for clapping during the Queen's Speech debate. So why is applause banned in the Commons?
You can wave your order papers, shout until you are purple in the face, hurl abuse across the Chamber, join in with frankly weird displays of mass groaning or that elongated "hear, hear" thing they do.
But try joining your party comrades in a sincere appreciation of a point well made in the traditional way and you will have Speaker John Bercow on his feet telling you to respect the traditions of the House.
At least, that's what the 56 new SNP MPs found on Wednesday, when they broke into applause to support Angus Robertson, their leader at Westminster, who was hitting back at a furious attack on the party by Labour MP Ian Austin.
"May I say at the start of the Parliament," said Mr Bercow, "that the convention that we do not clap in this Chamber is very, very long established and widely respected, and it would be appreciated if Members showed some respect for that convention.
"They will get their speaking rights from this Chair - of that they can be assured. They will be respected, but I would invite them to show some respect for the traditions of this Chamber of the House of Commons."
But like many other things in Britain's elasticated, unwritten constitution, the no-clapping convention is there to be broken.
The most famous occasion was on the 27 June, 2007 when Tony Blair gave his farewell speech to the House of Commons.
With wavering voice, the outgoing Labour prime minister admitted he was not really a Commons man, but he respected the place and the "noble" profession of politics, and with a final thespian flourish spoke his final words to the Chamber: "I wish everyone, friend or foe, well and that's that, the end."
A ripple of applause on the Labour benches soon spread across the floor before turning into an unprecedented cross-party standing ovation. It was an extraordinary scene - and one the then Speaker Michael Martin did nothing to stop.
John Bercow himself has not always enforced the no-clapping rule as vigorously as he did on Wednesday.
When the previous government mounted a last minute attempt to oust him as Speaker, on the final day of Parliament in March this year, Tory MP and friend of the speaker Charles Walker delivered an emotional speech denouncing what he saw as the underhand tactics of then-chief whip Michael Gove.
The Speaker's supporters got to their feet to give Mr Walker a standing ovation. A clearly overcome Mr Bercow let it go.
The history of applause
Making a noise with the hands to show appreciation or disapproval is as old as civilisation itself.
In ancient Rome, clapping was part of a repertoire of gestures, including the snapping of the finger and thumb and the flapping of togas, used by audiences at public performances.
In French theatre, groups of professional clappers, known as "claques", were hired by performers to make them appear more popular with audiences.
In politics, the length of the ovation at the end of a speech is sometimes seen as a sign of how well it went down.
This took on a more sinister dimension in Soviet Russia, when party leaders would give long speeches with orchestrated applause and ovations.
In the book Gulag Archipelago, author Aleksandr Solzhenitsyn recalls how someone toasted Stalin at a local Communist Party conference and "stormy applause, rising to an ovation", broke out. The great leader was not present but the applause continued regardless. "Palms were getting sore and raised arms were already aching... however, who would dare be the first to stop?"
So why is applause normally banned in the Commons?
There is certainly plenty of claptrap spoken in the House (in the traditional sense of the word, meaning something designed to elicit applause).
But MPs and members of the House of Lords are encouraged to find other outlets for their approval, mainly through the shouting of "hear, hear!", which started life in the 17th Century as a cry of "hear him! hear him!".
The rules are laid out in the Parliamentary etiquette bible Erskine May, which says: "Members must not disturb a Member who is speaking by hissing, chanting, clapping, booing, exclamations or other interruption."
But it adds: "When not uttered till the end of a sentence, the cry of 'hear, hear,' offers no interruption of the speech."
MPs are well aware of how absurd this can sound to the uninitiated.
The modernisation committee, set up by Tony Blair's government in an effort to drag the Commons into the 20th Century, said new MPs found it "incomprehensible that it is not in order to clap at the end of a speech, a practice which is commonplace in other gatherings and indeed in other Parliaments".
But the committee backed the applause ban in a 1998 report: "While we agree that spontaneous clapping at the end of a speech could in no way be interpreted as disturbance of the speaker, there is a danger that such a practice might be open to abuse and could lead in certain circumstances to orchestration of what would amount to standing ovations with the success or failure of a speech being judged not by its content but by the relative length of the ovation at the end.
"This might not disrupt an individual speech, but would disrupt the tenor of the debate, as indeed would slow handclapping."
So it looks as if MPs will have to continue sitting on their hands. And the SNP will have to find a new way to show their appreciation.