It's a much deeper question than it superficially seems, as it affects swathes of cultural material in museums in Britain now. It's all very well saying it was purchased by X or donated by Y but the fact remains, in the present, that nations now emerging from European hegemony feel a little sensitive about significant stuff that's goggled at in London or Edinburgh or wherever by millions of wealthy tourists who also want to buy the postcard and tshirt. The circumstances of sales and gifts often emerge as slightly unfair when re-examined now. If we were flat on our arrises as a country, pounded by war, governments in shreds, and some foreign bod said here's a few million for (say) the Sutton Hoo treasure, firstly we'd be daft not to accept and secondly if n when we got it together again we might want to go asking.