battle bus

plural battle buses

1. UKinformalA bus that is used as a mobile office and publicity centre by a politician or party during the run-up to an election

   Painted blue, the Battle Bus bore the slogan 'Moving Forward with Maggie'.

   1995, Margaret Thatcher, The Downing Street years

   3 more examples

   [Photo shows Steel sitting on a coach emblazoned with "DAVID STEEL'S LIBERAL BATTLE BUS". Photo caption reads:] STEEL'S ON WHEELS: Setting off from the National Liberal Club in his battle bus.

   1979 April 10, Ian Aitken, “PM smites the Tories with his crusading zeal”, in The Guardian, London: Guardian News & Media Limited, retrieved 13 May 2017, page 1

   Word comes from Edinburgh that our colleagues are rebelling against the LibDems' charge of £1300 for a seat on their battle bus which today, we hear, had only one passenger.

   2000, Murray Ritchie, Scotland Reclaimed: The inside story of Scotland's first democratic parliamentary election

   I remember in 1997 the BBC gave the Green Party five minutes to say whatever it wanted (within reason) and it chose to fill its slot with images of its activists on a battle bus, whizzing into a petrol station, leaping out and hurling abuse at people for filling their tanks.

   2006 October, ThirdWay, volume 29, number 8