Basically the title. Curious as French horn is obviously English and you would imagine that the English horn would be known as suck but we call it the Cor Anglais. Which is obviously French. How did this naming come about?
What, you expect logic in instrument names?
The French were the ones who coiled the tubing into the familiar round loops, but it was more commonly called a trompe, hunting horn, or cor de chasse, the Germans being the first ones to put it into the orchestra in the early 18th c. The term "French Horn" seems to date to Charles Claggett's 1788 introduction of interchangeable crooks that could be used for changing keys. The term English Horn seems to be mid 18th. c., with the term corno inglese appearing in Viennese scores circa 1764. So had anyone, including Claggett, wanted to call Claggett's innovation an English Horn, there would have been confusion.
Perhaps some players will speak up, but I think most say "horn" for French horn, just like the French themselves just say "cor", so confusion may be growing less.
Sibyl Marcuse : Dictionary of Musical Instruments