They're all lucrative positions, I do know the British Museum - or did, in 1933 - better than most. From my research, Cairo has changed considerably, and there's quite a lot of turmoil going on in Egypt at the moment. And there's a curfew, and we don't have the benefit of our mansion or will likely be able to afford anything nicer than a small apartment, given the state of affairs and over population.
London seems a fair bit quieter, and it would mean we'd have to keep up our travel budget and housing there is also a bit on the smaller side.