It's just surprising to me, in a nice way, that this stuff wasn't immediately consigned to BBC4. I suppose if you're going to get names like Tennant, Serkis and Broadbent, you'll have to justify it with audience figures. The story of Eddington verifying the General Theory of Relativity during a solar eclipse in 1919 is well covered in many popular physics texts; the back-story of what went on between him and Einstein during World War I was new to me.
I suppose if either of them had given it much thought, they would have found and corresponded through an intermediary in neutral Switzerland. Then again, it strikes me as something of a miracle that their correspondance could pass at all between Britain and Germany at that time.
Funnily enough, Eddington's sexuality doesn't form part of the regular write-up either, though I think his Quaker background is often mentioned. The play didn't seem to leave much to the imagination of modern audiences, but probably had enough get-out clauses too.
Overall, better than Hawking I think, but not as good as Frayn's Copenhagen.