The Chief Rabbi's visiting party was afforded a special dispensation to breach Vatican protocol.
Last Thursday's trip coincided with the date Rabbi Mirvis's communications director, Mark Frazer, was due to become a father again.
Mobile phones are banned during Papal receptions but Mr Frazer was allowed to keep his on him at all times in case wife Judith should call.
Fortunately, baby boy Frazer was born hours after his dad got home.