Australia could be without a chief diplomat in London for several weeks due to incoming high commissioner George Brandis tearing his Achilles.

The current High Commissioner Alexander Downer is due to leave his post on April 4 and has been farewelled in London by high-profile friends and colleagues.

It is understood his replacement, 60-year-old former senator Brandis, has had ongoing issues with his Achilles and his arrival in London will be delayed.

The injury comes at a crucial time in diplomatic politics for Australia, with the arrival of Prime Minister Malcolm Turnbull for the Commonwealth Heads of Government (CHOGM) meeting in Windsor beginning on April 19.

Mr Brandis is still expected to be there for CHOGM, despite his injury.

It was anticipated the event would be the perfect entry to diplomatic life in London for Mr Brandis, with the opportunity to make instant connections.

Diplomacy a slippery slope

This is not the first time incoming Australian ambassadors have done themselves an injury.

Kim Beazley slipped on an icy driveway leading to his new home in Washington DC shortly after he arrived in February 2010 to take up the post as Washington ambassador for Australia.

He injured one knee as he fell, and then as he pulled himself up he injured the other.

Mr Beazley was forced to arrive at the White House in a wheelchair to receive his official papers from the then-president Barack Obama.

An injured Kim Beazley exchanges credentials with Barack Obama. ( AAP Image/Official White House Photo )

And Russia ambassador Peter Tesch injured himself on his farm in Bega before starting his posting in January 2016 and was delayed in arriving to start his new job.

Mr Brandis's appointment had been long expected, but it was only formally announced by Foreign Minister Julie Bishop on Tuesday.

"Today I announce the appointment of The Hon George Brandis QC as Australia's next High Commissioner to the United Kingdom," the media release dated March 20 read.

"I thank outgoing High Commissioner, The Hon Alexander Downer AC, for his significant contributions to advancing Australia's interests in the United Kingdom since 2014, and also for his distinguished career advancing Australia's foreign, trade and development interests over a lifetime of public service."

It is unclear how Mr Brandis aggravated his Achilles or precisely when he will arrive in London.