Outgoing Attorney-General George Brandis has admitted that leaving politics to become Australia's High Commissioner in London was not his idea.
Prime Minister Malcolm Turnbull will formally propose Senator Brandis for the new role early next year after calling time on 17 years as a Queensland senator.
After conceding the appointment was Canberra's "worst-kept secret", Senator Brandis denied he was told his time was up due to poor ministerial performance.
"I wouldn't say it was my idea," Senator Brandis said on the ABC's 7.30 report on Tuesday night.
"It was something that developed in discussion and it was something that I was attracted to."
Senator Brandis said he did not believe colleagues were plotting to push him out of parliament when discussions about taking up the diplomatic position started earlier in the year.
"It is a post that I have often thought would be a post for which I would have certain suitabilities," he said.
Mr Turnbull paid tribute to the former cabinet minister, who will replace one-time federal Liberal leader Alexander Downer in London, where he has spent three years as High Commissioner.
"It is a very, very important time in the history of the United Kingdom and there is a lot at stake for Australia in our relations with the UK," Mr Turnbull said in announcing a cabinet reshuffle on Tuesday.
Senator Brandis, a key advocate within the coalition for legalising same-sex marriage, leaves parliament after seeing the law passed on his final day in the Senate.
Mr Turnbull said the historic change happened in no small measure to to his "eloquent advocacy".
The prime minister also praised Senator Brandis over a national security review which resulted in foreign interference legislation which is before the parliament.
"The most sweeping reforms ever made to keep us safe from hostile foreign interference are his handiwork and will be an important part of his legacy," Mr Turnbull said.
In 2014, Senator Brandis famously declared people had the "right to be bigots" during a debate on changing racial discrimination laws.
The Queen's Counsel last year had a high-profile bust-up with former solicitor-general Justin Gleeson, who subsequently resigned over the pair's "broken" relationship.
The 60-year-old entered parliament in 2000 and was made arts and sport minister in 2007 under John Howard.
When the Tony Abbott-led coalition came to power in 2013, Senator Brandis became attorney-general and arts minister.
