The likely re-election of Prime Minister Boris Johnson will not end the Brexit uncertainty for Japanese firms that are also worried about the impact of his "hard Brexit" vision for the country, according to trade experts.

Polls indicate Johnson's Conservative Party will win a majority in December's general election, leading to Britain's formal departure at the end of January and then negotiations on a free trade agreement.

Johnson says the trade deal has to be in place by the end of next year, leading to fears of another no-deal cliff edge for Japanese firms that, along with the rest of British industry, have been hampered by parliamentary deadlock on the way ahead since the 2016 referendum result.