Quote: garyhulsefan "Although the comments are posted from France the comment can be read here in the UK so he has been defamed in this country and can take court proceedings here if he wishes.'"
This.
Same reason Russian oligarchs can sue each other here in the UK, where defamation cases are much quicker to process and easier to bring than back home.
You can bring proceedings in any country in which you can show you have been defamed - basically pretty much anywhere the comments could have been read.