Gallagher lodged paperwork, in line with a new parliamentary register of citizenship, today confirming she completed a British citizenship renunciation form, with payment, on April 20, 2016.

But the UK Home Office wrote back on July 1, almost a month after election nominations closed, requesting original copies of her birth certificate and parents’ marriage certificate.

Gallagher did not receive the formal renunciation document until August 16.

Her father was born in the UK in 1939.

In the mid-1990s she investigated the option of moving to the UK to work.

When she made inquiries at the time, British authorities told her she would need to go through a formal application process and if she did so it was likely she would be granted citizenship although it was not automatic.

The ACT senator told parliament in September that during the 2016 pre-election candidate vetting process Labor officials had advised her “out of an abundance of caution” she should fill out a form renouncing her British citizenship.

Her disclosure had all of the information available to her over her eligibility, Senator Gallagher said in a statement.

“Legal advice was provided to me by Dr Matthew Collins QC and an expert in British Nationality Law Mr Adrian Berry,” she said.

“Mr Berry finds that ‘…. Senator Gallagher had, prior to the date for nominations for the 2016 election, taken all of the steps that were required to be taken by her (not just the reasonable steps required) under British law in order to renounce her British citizenship’.”

Gallagher said based on her legal advice she did not believe she should refer herself to the High Court.

“However ultimately that will be a matter for the Senate to determine.”

There could also be questions in regard to Nick Xenophon Team senator Rex Patrick, who replaced his party’s leader in a casual vacancy.

Patrick was born in New Zealand did not renounce his NZ citizenship until October 16 this year, which would have made him ineligible to run for the 2016 election.

Xenophon resigned from the Senate on October 31.

Australian Conservatives leader Cory Bernardi revealed his father and paternal grandparents were born in Italy, however, his father became a sole Australian citizen prior to Bernardi’s birth.

He declared he had lodged a form renouncing Irish citizenship in 2006, having held an Irish passport since 2004.

But there was no evidence provided by the Irish government on his renunciation.

Liberal Democrats senator David Leyonhjelm made a mockery of the citizenship declaration process.

“I once asked my mother if my father was truly my father, but she was offended so I didn’t ask again. I suspect immaculate conception,” he wrote.

– AAP