Looks odd alright as poster campaigns like that are usually for people on shanks pony. I can only suggest they have taken blanket coverage across the south east with the intention of catching commuters who have cars at home.
By the way Seafrance have very cheap deals this weekend coming. Have had a press release to that effect and will get it up tomorrow on f/p. havent had a chance to have a proper look at it yet but looks to be a good deal on offer.