I would have said Petula Clark, but I'm sure she wouldn't be the only Brit to have had multilingual hits; it used to be quite common for songs to be released by the original artist in the language of the country of release. They used to learn the lyrics phonetically, and I guess there would be a few odd moments for the local listeners - like the one you get in an overseas hotel bar when the vocalist has "learnt" a song in English from listening to it. Pet Clark, on the other hand, is fluent in French and I think speaks quite good German too, so she would have been in a position to release songs specifically for those markets in their own languages. incidentally, she also had hit songs in Italian, so that would be four languages........