But he couldn't prove it.

He had no documents to back up his story; and neither, it seemed, did the UK Home Office. Meaning no such documents existed.

He looked like a complete dill, of course, but instead of wasting the High Court's time in a cynical bid to cling to his job he did the right thing: within a few days he had resigned from his seat, sparking an immediate byelection.

When Labor MP David Feeney was first outed as a potential UK dual citizen he tried to claim he was in the clear because he himself had renounced.

But he couldn't prove it.

He had no documents to back up his story; and neither, it seemed, did the UK Home Office.

Seven weeks later, it's hard to escape the conclusion that for David Feeney too, no such documents exist.

And yet still, he's off to the High Court.

Instead of doing the right thing, Feeney is staging a cynical bid to cling to his job - or at least to buy some more time.

Why the delay? That's simple.

Unlike Alexander, Feeney is likely to lose. The Greens are on the march in Feeney's seat of Batman, with a strong candidate who has run twice before and has all the momentum after last year's Northcote contest.

Is the ALP trying to find a new candidate? A Kristina Kenneally-type who might be able to reverse some of the damage Feeney has done in the seat? Maybe, although that might not be enough to stymie the Greens.

What's certain is this: if David Feeney rocks up to the High Court with no compelling proof that he took reasonable steps to renounce his UK citizenship he'll look every bit as foolish as One Nation's Malcolm Roberts.

He should save himself the indignity - and save taxpayers the court costs - and resign now.