1925 Southern Railway poster for Londres (London), so clearly aimed at the French (or posibly Belgian) market. I have seen the poster described as 'anon by Waterloo & Sons' but this is probably a typo. Waterlow & Sons was a printer especially of postage stamps, currency and bond certificates.
The image shows a view from above the Houses of Parliament, looking East up the Thames with Westminster, Hungerford and Waterloo Bridges over the river.
The simple text names five crossings: Calais-Douvres (Dover), Boulogne-Douvres, Boulogne-Folkestone, Dieppe-Newhaven and the less common Le Havre-Southampton.
Artist? Unknown, sadly.
Keywords: 1925; Southern Railway; British Railway; poster; advert; plakat; affiche; Londres; London; Paris; Calais; Dover; Douvres; Boulogne; Folkestone; Dieppe; Newhaven; Le Havre; Southampton