Some of the Frenchmen I know with English names (the pronunciation differs, obviously, but not the spelling)
Christian
Eric
Francis
Frank
Jeremy (but with accents on the two e's)
If you look up the 100 most popular boys' names in France, a whole host are both English and French, or English rather than French, e.g. William rather than / as well as Guillaume, for example.
The first group: Nicolas, Hugo, Paul, Victor, Theo, Simon, Nathan, Jonathan, Damien, Martin, Dorian, Samuel, Gabriel, Marc, Adam
The second: William, Tom, Robin, Steven, Tony, Gregory (with an accented e), Anthony, Christopher.
Also Welsh and Irish names feature – Alan, Dylan, Morgan, Kevin, Killian, Tristan.