Constantinople, Byzantium and Istanbul

So what should you call it? Well, Istanbul, obviously - I can only explain my lapse by reference to listening to John Julius Norwich on Radio 4 yesterday. But shouldn't that have made me call it Byzantium? What is going on? Incidentally, I recommend Procopius' 'Secret History' to anyone interested in Byzantine history. The dirty bits are on page 40 (and indeed much of the rest of the book).