In the British House of Commons on 13th June 2018, SNP MP Ian Blackford said:
"Under the circumstances, given the disrespect that's shown, I have got no option but to ask that this House now sits in private."
What does asking for the House to "sit in private" mean?
The meaning is actually relatively literal. The BBC summarises it here:
Parliament retains the right to hold debates in private and any MP can propose that members of the public and press be removed from the galleries at any time.
If such a proposal is made, the Commons Speaker must put the motion "That this House sit in private" to a vote without debate.
But the procedure is seldom successful - attempts to exclude members of the public are usually deployed as a device to disrupt or delay the House's proceedings.
In case it's not clear, 'galleries' should be interpreted as 'viewing areas into the debate hall'.
This refers to making a motion under Standing Order 163, which states:
If at any sitting of the House, or in a committee of the whole House, any Member moves ‘That the House sit in private’ the Speaker or the chair shall forthwith put the question ‘That the House sit in private’, and such question, though opposed, may be decided after the expiration of the time for opposed business, but such a Motion may be made no more than once in any sitting:
Provided that the Speaker or the chairman may, whenever he thinks fit, order the withdrawal of those other than Members or Officers from any part of the House.
An order under paragraph (1) of this order shall not apply to members of the House of Lords.
According to paragraph 17.22 of Erskine May, if a motion under this standing order is agreed to, then "all the galleries are cleared, including Hansard reporters, with the consequence that there is no report of debates; broadcasting also ceases. The occupant of the Chair may authorise a short suspension to allow these arrangements to be put in place".
Paragraph 6.57 also notes:
Such an order extends to the Press Gallery and requires broadcasting to cease. Following the private sitting in 2001, the sound amplification system has been modified so that it can be used when broadcasting has been turned off.
The majority of uses of this standing order are to engineer an immediate division. Standing Order 41 requires that if fewer than forty MPs take part in a division, the current business under consideration "shall stand over until the next sitting of the House", and the House moves on to the next business. MPs seeking to derail a poorly-attended private member's bill debate, then, can move that the House sits in private, and hope that fewer than forty members take part in the division. If this is the case, the debate on the private member's bill will be adjourned due to the House being inquorate.
