mystery tour

plural mystery tours

1. UKA short-duration outing by coach to a destination that is not revealed in advance

   I recall, Anderson went on, the fine story of a Welsh mystery tour by bus from Cwmrhydyceirw in my constituency.

   1999, Vernon Bogdanor, Devolution in the United Kingdom

   1 more example

   Each week an inconspicuous paragraph in the daily press carries a warning to travellers on the London Midland Region of the delays and diversions to be expected on account of the weekend's engineering works. In fact, Sunday travel on the West Coast route has now become a kind of mystery tour which can prolong the London-Glasgow journey to twelve hours or more.

   1960 October, J. N. Faulkner, “The purgatory period of B.R. Modernisation”, in Trains Illustrated, page 584