From an Egyptian viewpoint - a good example might be as follows:
What if an artifact was found in the Gaza Strip in 1955 and taken to the UK, who should the UK return it to? The Gaza Strip government, the West Bank government, the Israeli government, or the Egyptian government?
Edit: cannot reply below -
1. I'm pointing out a specific requirement in IR
2. The Gaza example above is an analogy for the Kohinoor example. I honestly don't care about the Egyptian case because I have no connection with that part of the world and I assume there are different considerations.
Also the Gaza strip example is just unnecessary hypothetical scenario. The British and french stole a lot of things from all over Egypt. There is no need to imagine hypothetical scenarios.