An estimates hearing fired up yesterday, with the Opposition digging into every detail of the Prime Minister Kevin Rudd's staff even questioning who looked after his pets' ''toileting arrangements''.

But the focus was on two assistants.

Liberal senators outraged Special Minister of State John Faulkner by labelling a Lodge ''household assistant'', who also looks after 14-year-old Marcus Rudd at times, as a nanny, after quizzing him about a mystery personal assistant travelling with Mr Rudd on his recent 17-day world trip.

Liberal senator Michael Ronaldson led the charge on the personal assistant, asking ''How many working families have a butler?''

''The Opposition believes that this person, who I think we probably in the circumstances need to call Jeeves not his proper name, which is not appropriate to mention but Jeeves, the Opposition believes, actually travels with the Prime Minister, may well even assist the Prime Minister at Kirribilli House, certainly travels with him overseas and he takes on the role of a butler,'' he said.

He understood the man had been laying out Mr Rudd's clothes for him at times during the world trip, and questioned what his role actually was.

''If he puts out the ties and polishing shoes in the morning he's probably a valet. If he gets a cup of tea in the morning he's probably a butler, and if he carts the luggage around he's probably a footman,'' he said.

Senator Faulkner said the man was an executive assistant in Mr Rudd's office, responsible for managing ''the Prime Minister's paper flow''.

''That particular staff member assists with invitations, gifts and travel arrangements,'' he said.

''... this description ... of the staff member's role is absolutely inappropriate and absolutely offensive to all concerned, but most importantly I believe to the staff member concerned.''

He was also upset at the Opposition repeatedly referring to a household assistant at The Lodge as a nanny.