Manchester: Former prime minister Julia Gillard is set to speak at Boris Johnson's first Conservative Party conference as Prime Minister.

The former Labor prime minister will speak on a panel to discuss international aid and education, in her capacity as chair of the Global Partnership for Education.

The surprise appearance from Australia's first female prime minister comes after the Supreme Court ruling which cut short the Labour Party's conference in Brighton last week threatened to overshadow Johnson's prime ministerial debut before the conference in Manchester.

Gillard did not attend Labour's conference, but her close ally, former treasurer Wayne Swan, and the new Labor Party national secretary Paul Erickson were observers.

Labour members planned a major "Shut Down the Tories" rally in Manchester as speculation mounted the recall of Parliament, triggered by last week's court ruling that Johnson unlawfully shut down Parliament, could see the event abandoned by key MPs now required in the Commons where Johnson has a majority of minus 40.

Johnson arrived in Manchester arm-in-arm with his 31-year old girlfriend Carrie Symonds, but his prior relationship with another blonde is in focus.

The Sunday Times reported that Jennifer Arcuri was given $228,946 in public money and privileged access to three foreign trade missions led by Johnson while he was mayor. It said Acuri told four friends that she was having an affair with the then London mayor.

Speaking to the BBC's Andrew Marr Show, he said: "Everything was done with full propriety...there was no interest to declare."

Tony Blair's former communications director Alastair Campbell said the story warranted scrutiny.

"Am normally opposed to private life Qs of politicians on TV but given financial and other advantages given by a public official to Ms Arcuri the direct question of Boris Johnson ‘have you ever had sex with her?’ is a legitimate one," he wrote on Twitter.

"If not asked it’s another fail for journalism."