Jack Walker worked in the office of Australia’s Defence Industry Minister Christopher Pyne. He handed in his notice upon returning to Australia yesterday.

Australia’s ABC News, reporting Walker’s resignation, quoted Pyne as saying that Walker had indicated his “deep regret for causing any embarrassment to the Government” and apologised for his action.

The nine Australians – dubbed the Budgie Nine – were Walker, Timothy Yates, Tom Whitworth, Tom Laslett, Nick Kelly, Edward Leaney, Branden Stobbs, James Paver and Adam Pasfield.

They had pleaded guilty at the Sepang Sessions Court for causing public nuisance under Section 290 of the Penal Code, and had been let off with a caution.

All nine admitted stripping down to their underwear bearing the printed national flag, when celebrating the victory of their fellow countryman Daniel Ricciardo at the Formula One Malaysian Grand Prix.

Through a spokesman, the nine issued an apology in court saying they had “no intention of undermining this country and its sensitivities” with their act.