The UK government occasionally does give things back on the understanding that they can be returned for a bit when required...
I don't really see how that example is "giv[ing] things back." That stone is still the property of the British government and kept continuously on British territory.
The Stone of Scone getting returned to Scotland is a bad example. Sure, it’s symbolic, but Scotland is in the UK and so this was really just moving something around within the UK borders.