Analysis by Fairfax Media shows 49 per cent of Liberal MPs have worked in state and federal politics before being elected, up from 36 per cent in the 44th Parliament.

Inside the Labor caucus, 55 per cent of MPs have previously worked as staffers, electorate officers or advisers before being elected, while 40 per cent have previously worked in roles within the trade union movement.

Before 2016 election, 42 per cent of cabinet ministers had been employed as staffers and party officials. In the current Turnbull government cabinet, that number has risen to more than 50 per cent.

Opposition Leader Bill Shorten's frontbench includes 40 per cent former trade union officials.

Before the election, 13 per cent of Nationals MPs were former staffers or ministerial advisers, rising to 18 per cent in the 45th Parliament.

The number of female Liberal MPs dropped to its lowest number in 25 years in 2016, with just 13 women sitting on the government benches in the House of Representatives.

Melbourne University principal fellow Nicholas Reece said elected representatives should have a diverse range of backgrounds, and the increasing proportion of career politicians has helped fuel voter anger at politics around the world.

"The fact that Ben Chifley was a train driver who became a magnificent post-war prime minister and Pauline Hanson was a fish and chip shop owner are both examples of people with everyday backgrounds that can be highly appealing to the electorate," he said.

"These high numbers do reinforce this insiders and outsiders cleavage in Australian politics, which we know people are expressing their frustration with in spectacular fashion in events like the election of Donald Trump."

Mr Reece, a former staffer for Julia Gillard and Labor premiers, said working for members of parliament also provided an important training ground for future local political leaders.

"It is also true that politics is a really tough game and a lot of representatives come from these backgrounds shouldn't surprise us, and in some respects mean they come to the job knowing what's involved and having some training in the tasks," he said.

A Parliamentary Library report in 2013 said "the era of the career politician is not over". It found a slight reduction in the professionalisation of Australian politics as the average length of service by MPs fell.

Politicians elected in the early years of federation served an average of 10.6 years, rising to 14.1 years in the period immediately after World War II, while between 2000 and 2012 the average completed term dropped to 13 years - including 12.6 years for members of the House of Representatives and 14 years for senators.

"Labor has come under criticism in recent years for the high proportion of its representatives who have a union or staffers background," Mr Reece said.

"The Liberal Party can equally be criticised for the narrowing of the pool from which it draws its candidates with the rise of former staffers in its parliamentary ranks."

Tim Wilson

Present: Liberal Member for Victorian seat of Goldstein

Past: Electorate officer, project manager, consultant, Institute of Public Affairs, Human Rights Commissioner

Nicolle Flint

Present: Liberal Member for the South Australian seat of Boothby

Past: Lawyer, corporate affairs director, Menzies Research Centre fellow, policy adviser to state and federal MPs and ministers

Julian Hill

Present: Labor Member for the Victorian seat of Bruce

Past: Electorate officer to Alan Griffin MP, City of Port Philip mayor, Victorian departments of environment, planning, economic development

Justine Keay

Present: Labor Member for Tasmanian seat of Braddon

Past: Supermarket manager, TV traffic clerk, administrative assistant to state environment minister, personal assistant to deputy premier, adviser to Tasmanian premier Lara Giddings