open-top bus

plural open-top buses

1. UKtransportA double-deck bus with an open, or partially open, top deck.

   1 more example

   At last the first glimpse from a bridge of an open-top red bus, and a noticeable darkening of the atmosphere from the smoke of London: then the increasingly dingy stations with double-barrel names, set amid what has always been to me the outstanding feature of the "Premier Line" approach to London—the positively marvellous display of crazy chimney-pots on the grey inner suburban houses. As many as twenty, all of varying style, standing together like ranks of jagged teeth, and providing a Dickensian back-cloth which no other route can boast.

   1951 October, R. S. McNaught, “Lines of Approach”, in Railway Magazine, page 704

   Synonyms: open-topper