I would like to point out, that Neil posted this behind the scenes picture of Crowley’s Mona Lisa sketch from Leonardo da Vinci (x):
Where the inscription is:
Al mio amico Antonio dal tuo amico Leo da V. meaning To my friend Anthony from your friend Leo da V.
Which means that around 1500 Crowley had already chosen ‘Anthony’ and then spent at least 440 years hiding it - perhaps for the reason that the angel would not like it - from Aziraphale until the Nazis outed it…
I think Aziraphale is just a drama queen who preferes the name Antonio. His friends at the Hundred Guineas Club thought he had some exotic Italian lover in his past, and he loved that they thought that (for some reason he couldn't tell you why though...)