Australia has said it is willing to wrap up a trade deal with the UK in less than a year, if immigration restrictions are relaxed between the two countries, according to a top diplomat.

Australia’s high commissioner to the UK, Alexander Downer, said a quick free trade agreement would be possible once there was more clarity from the government about post-Brexit priorities, in an interview with the BBC.

Freedom of movement would be a central part of any deal, Downer said, to increase the ease of investment in both directions. This could take the form of a simplification of the current tiered UK visa system, under which skilled workers who have been offered a job can enter the country.

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“We would want to see greater access for Australian businesspeople,” he said.

The Australian government is already in high-level discussions with the UK government about the scope of an agreement, he said, although no deal will be possible legally until the process of leaving the EU is complete.

Downer pointed to the example of the US free-trade agreement with Australia, which was completed under the respective leaderships of George W Bush and John Howard. That agreement was completed within eight months.

The pace of those negotiations was helped by the “political will” to get a deal done, Downer said. Australia would be a “pretty open partner to deal with” in any similar negotiations, he said.

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However, any agreement would have to be comprehensive, rather than an agreement on reducing tariffs for some sectors. This has the potential to conflict with some of the promises made during the EU referendum campaign, when some claimed leaving the EU would enable the UK to raise tariffs to protect British industry.

“It depends what Britain would want to protect, and we have no sense of that at the moment,” said Downer.

Furthermore there could be some complications around the sometimes “difficult” process of harmonising regulations, he said.