This is the partner to Victoria Dunkerque at night, but from the French perspective. Although I can't confirm this, I assume that like its counterpart it's a 1932 work by Cassandre. The poster was produced by the three parties to the service - the Southern, Northern Railway (Chemin du Fer du Nord) of France and ALA Steamship Company (Societé de Navigation ALA).
I found this image on the web. To my eye, the colours don't look at all authentic, especially when compared with its partner. The perspective on the version I found looked strange, too - too wide - so I've corrected that to be consistent. It may well be that the proportions of the original were different because of alternative publishing sizes in France, but in the absence of an original I'm unable to determine the truth.
If you're lucky enough to have an original or other published version of this poster it would be great if you could let us know.
For comparison the version on the right is in the web 'original' (but probably incorrect) proportions but with the colour mix manipulated to be closer to the partner, courtesy of Lordprice.
Keywords: Southern Railway; poster; Cassandre; cross-channel; London; Londres; Victoria; Folkestone; Dunkerque; Dunkirk; ALA Steamship Co; Societé de Navigation ALA; Northern Railway; Chemin du Fer du Nord; new night service; Ligne Francaise de Nuit;