yes.... people visit the British museum to view British history and artifacts not items that's been pillaged from other countries or is that the type of history that us British people want to show the world?
It's fine when museum borrow or lend artifacts from other parts of the world for a short period of time to allow people who don't/can't travel to see them.
It's not like the Briish museum is making money from them, it's free to go into the museum and it's probably costing us the british tax payer some amounts per year just maintain them while we keep them here.
EDIT: Earl of Elgin purchased them for his private collection from the Ottoman Empire when they was in control of Greece, the only reason why the British museum has them, is because he re-sold them when he was broke.. Even at the time it caused a stir...
Lord Elgin went beyond his original mandate, amassing a vast store of treasures, one scholar notes.
daily.jstor.org