During their visit to France in 1938, King George VI and Queen Elizabeth proceeded from Calais to Paris in Pullman car hauled by a streamline locomotive:
The loco chosen for the Royal train was the SNCF 231C78, the one and only C-class Super Pacific fitted with streamline shrouding. Initially designated Nord 3.1280, it belonged to the third batch of the 231C class, designed by Marc de Caso in early 1920s for Paris - Lille service. The task was to provide the railway with a top-performance steam locomotive capable of hauling a 300-ton passenger train at speeds up to 120 km/h. Being past and powerful, the Super Pacifics were somewhat conservative, lacking mechanical stocker for coal feed. Their cab was not fully enclosed, earning a nickname "The rendezvous of winds".
The 3.1280 entered service with Chemin de Fer du Nord, bearing a special "winged" livery. Soon the railway was absorbed into a new state-owned company, SNCF. The loco was renumbered and received a new color scheme, light blue. For the Royal visit, French and British national colors were added (you can see a color rendering here). The cab remained only partially enclosed:
Some more pictures:
Watch a model of 3.1280 in its original 'chocolate' livery: