When promoting your country's glistening blue seas and golden beaches, it is probably best to ensure that you are using photos of beaches that are actually in your own country.
Unfortunately for the French tourist board, that is exactly what they didn't do.
After spending nearly £600,000 on an extensive advertising campaign on the London Underground, one sharp-eyed South African noticed that, in a series of adverts, the beach purporting to be on the south of France is actually Llandudno Beach, Cape Town.
The two beaches could hardly be further apart, with roughly 10,000 miles between the two. Or, to put it another way, nine days and 21 hours drive from each other.
Above: The advert as it appeared on the website...
Above: And a view of Llandudno Beach, Cape Town.
The flaw was spotted by Bradford Bird, born and raised in the Llandudno district of Cape Town. Bird said: "I grew up in Llandudno and so I recognised the beach as soon as I saw it.
"I thought 'that's a little bit cheeky' and put a picture of the billboard up on my Facebook page".
The French tourist board replaced the pictures on their website , however it is too late to do anything about the 460 adverts pasted up in Tube stations across the capital.
Above: The new photo, which is presumably now a French beach
The mistake has been attributed to a search error, rather than an intentional ploy to deceive potential holidayers.
This isn't the first time, however, that French travel adverts have put the country in hot water. In January, La Redoute unintentionally posted pictures of children on a beach, with a very visible naked man in the background.