Pairing is an arrangement between two MPs of opposing parties that allows them, with the agreement of the Whips, to miss occasional votes in the House.
If two members from opposite sides of the House both agree to miss a vote, then by agreeing to differ they would cancel out each other's vote, so neither Member need turn up.
MPs are generally only allowed to pair on votes that are not three-line whips.
Normally, the relationship between pairs is long-lasting and the system brings together some strange bedfellows. Labour MP Marjorie Mowlam and Conservative Cabinet minister Michael Portillo were an established pair before the 1997 General Election.
It is often difficult for new MPs to find an available backbencher to pair with.
Where the government side has a large parliamentary majority, some MPs will be without a pair so, except for crucial votes (some three-line whips), a number of unpaired MPs may be allowed to be absent at specified times on a rota basis. This is known as a bisque.