British Foreign Secretary Boris Johnson has likened Brussels bureaucrats to the "finger-cracking" divorce lawyers employed in Sir Paul McCartney's bitter split with Heather Mills and suggested his government may need to appeal directly to national governments to manage Brexit negotiations.

Mr Johnson, who also said Australia should be "at the front of the queue" of potential British free trade partners, told a private Australian Business UK function in London late last week that mutually-beneficial Brexit talks will depend on the "frame of mind" both sides adopt once Prime Minister Theresa May formally triggers the process before the end of March.