Should the British Museum only have items from the UK?

Yesterday, Rishi Sunak declined to see the Greek Prime Minister because he answered a question about The Elgin Marbles.

I understand the desire of Greece to have them back, but as has been pointed out, many nations want items in The British Museum to be returned to them.  I guess it can be argued that no nation should have items in a museum that do not belong to that country.  I am of the opinion that this is not of any use in teaching people about history of other nations.  I do think that there could be more sharing of the more mobile items across borders but when it comes to the treasures looted by The British Empire, they should stay.  

However, it is silly for Sunak to act in the manner that he did.  I would expect our politicians to speak to nations like China and Saudi Arabia about human rights.  I think it is right for the Greek Prime Minister to bring up an issue of importance to Greece.