A senior ministerial adviser who quit over his part in the "budgie nine" scandal was initially hired to answer phones and do some diary work, Peta Credlin says.

Former prime minister Tony Abbott's chief of staff said she would have thought that Jack Walker, 26, wasn't up to the position he eventually filled, policy adviser to defence industry minister Christopher Pyne.

Mr Walker and eight friends attended the F1 Grand Prix in Sepang, Malaysia, celebrating Australian Daniel Ricciardo's win by stripping down to their budgie smugglers emblazoned with the Malaysian flag.

They spent four nights in a Malaysian jail before being cautioned and released. Mr Walker resigned at the weekend.

Under Tony Abbott, Ms Credlin played a key role in hiring ministerial staff members. She said she adopted the same rigorous employment model for ministerial staff as operated under the Howard government.

"I'm told that it doesn't really exist any more under Malcolm Turnbull. These are serious jobs," she told the Sky News Andrew Bolt program.

Mr Walker was hired under the Abbott government, she said.

"But he was hired to answer the phones on Christopher Pyne's reception desk and do a bit of diary work. He was not hired as he was later on as a senior defence adviser," she said.

Ms Credlin said she started out as an electoral officer and it took her 16 years to work for the prime minister.

"Coming in at 22 and you are 10 foot high and bulletproof and you know everything, you are only going to come a cropper with that sort of attitude," she said.

AAP