[3] Leigh's maternal grandfather, a boilermaker and Methodist lay preacher, used the family's spare room to shelter a constant stream of refugees from places like Cambodia and Chile, who were escaping the regimes of Pol Pot and Augusto Pinochet.

[9] Leigh is one of at least ten MPs in the 47th Parliament of Australia who possesses a PhD, the others including Anne Aly, Jim Chalmers, Andrew Charlton, Daniel Mulino, Jess Walsh, Carina Garland, Adam Bandt, Mehreen Faruqi, Anne Webster and Helen Haines.

[10] Before entering politics, Leigh worked as a lawyer for Minter Ellison in Sydney and Clifford Chance in London from 1995 to 1997.

[12] Over his academic career, Leigh has published over 100 journal articles in the disciplines of economics, public policy and law and over 200 opinion pieces.

[13] In the 1995 NSW election, Leigh stood as the Labor candidate for the New South Wales state seat of Northcott, receiving an 8-point swing, but nonetheless losing by a large margin to Barry O'Farrell of the Liberal Party.

[11] On 24 April 2010, Leigh was selected as Labor's candidate for the Australian federal seat of Fraser[15] following the announced retirement of Bob McMullan.

[22] In a 2002 book he co-edited with the political scientist David Burchell, The Prince's New Clothes: Why Do Australians Dislike Their Politicians?

Leigh suggested a more aggressive media, which covers politics like sport and gossip, and a general breakdown in "interpersonal" trust were largely responsible for politicians' falling stocks.

In making his first speech, he identified the American liberal Senator, Daniel Patrick Moynihan, as his role model.

It’s not something that stopped with the end of the First World War or with the death of Ben Chifley....To me, the Australian project is about encouraging economic growth, while ensuring that its benefits are shared across the community.

[23] He believes growth comes with free markets and innovation — and he strongly identifies with the liberalism of Australia's second Prime Minister, Alfred Deakin.

[25] In the digital age, that liberalism means a market that is free to develop technological innovation, even with its "creative destruction".

[3] Leigh has observed that Australians also 'bowl alone', as they are financially stretched, time poor, and unable to make regular commitments.

This award, presented once every two years, is given to "honour that Australian economist under the age of forty who is deemed to have made a significant contribution to economic thought and knowledge".

[45] Speaking of the Christmas card in 2019, Leigh said, "people didn’t want to see airbrushed politics; they preferred to know that our kids were just as grumpy as everyone else’s".