Odgers’ Australian Senate Practice states (p. 149)
While in office the President is entitled to the title “Honourable”. When the President leaves office, the practice is that the title may be retained only if authorised by the monarch.
A list of former presidents of the Senate shows they have all retained the title ‘honourable’.
Parry’s behaviour in not admitting his potential UK citizenship is hardly honourable – it was duplicitous and cowardly. As it turns out, he was never eligible to be a senator, and therefore never eligible to be Senate President. He should not retain the title ‘honourable’.
The Government should ensure that Parry cannot carry that title.