I can't agree with supporting the return. Had they not been taken to England, we would not have them now. In the British museum, you can see copies of some of the marbles that were not taken to England, and the copies are now all we have left - the originals that had been left in Greece are now lost. The truth is that taking them to England saved many of these marbles from destruction.
Moreover, London is more accessible than Greece - if they had been left in Athens I likely would never have had the chance to see them in person, having never been to Greece, and no plans to do so in the future. London is a lot closer to people in America and most of the people in western Europe.