"makes Diana of the Ephesians look positively nipple-less"

Artemis of Ephesus. 1st century CE Roman copy of the cult statue of the Temple of Ephesus.
Public DomainArtemis of Ephesus. 1st century CE Roman copy of the cult statue of the Temple of Ephesus. - Credit: Pvasiliadis
The Ionian city of Ephesus was known for its temple to Artemis, or Diana.

Diana of the Ephesians was the goddess of fertility and was depicted as many-breasted, hence Aziraphale’s comment. She is also mentioned in Acts 19:28, where Ephesian metal-smiths shouted her defence, “Great is Diana of the Ephesians” against St Paul’s preaching of Christianity.