royal train

plural royal trains

1. rail transportA set of railway carriages dedicated for the use of the monarch or other members of a royal family.

   The Royal Train which will be used for the forthcoming tour of the King and Queen and the Princesses through the Union of South Africa will consist of 14 coaches, of which eight have been built recently by the Metropolitan-Cammell Carriage & Wagon Co. Ltd.

   1947 January and February, “South African Royal Train”, in Railway Magazine, page 36

2. A special train carrying royalty, including such vehicles.

   1 more example

   The Royal train, which was preceded by a pilot train for officials, journalists, and photographers, was made up of twelve cars (baggage car, composite baggage and staff sleeping car, business car, dining car, three compartment cars, two chambrette sleeping cars, a private car for the Prime Minister of Canada, and two Royal cars.

   1939 September, “The Royal Train in Canada”, in Railway Magazine, page 202