actually the brits have agreed to return the marbles.
they will be returned and housed in a new museum next to the current acropolis museum.
There are some "face saving concessions" in terminology but they are returning.
Some the british inteligencia are upset about the return, they fear a line of nations demanding returns and there is the natural "we're smarter than you about your antiquities."
(Actually, if this catches on, places like the Smithsonian and MOMA are going to lose a lot of their exhibits as well. Not everything therein is American-made or born).