three-line whip

From the triple underlining of very important votes on "the whip" — a document detailing upcoming business distributed weekly to British MPs by party managers.

three-line whip (plural three-line whips)

1. (Britain) A directive to MPs from party leaders to vote in a particular way in parliament, despite what the MP might believe or what his or her constituents might like.
   • 2008 April 12, Simon Jenkins and Richard Harries, Atheist versus Bishop, in The Guardian:

     Since the metaphysical status of egg-casing is not one on which the church has yet pronounced, opposition appears based on "yuck" and nothing else. But yuck has become diktat, with Catholic MPs up to cabinet level being given a three-line whip by their bishops.

2. (by extension, humorous) An imperative order.

   I have to go shopping with the wife, I'm afraid. She's given me a three-line whip.

• single-line whip, one-line whip
• two-line whip, double-line whip