[citation needed] He joined the Australian Labor Party in 1975 and was a public servant and electorate secretary to Senator Gareth Evans before entering local politics serving as a councillor in the Coburg City Council from 1981 to 1988.

"[12] The Sydney Morning Herald coverage emphasized that Kevin Rudd was under pressure over "allegations surrounding his past meetings with disgraced former Western Australian premier Brian Burke";[12] and that Thomson "had no choice but to resign, especially since [Prime Minister] John Howard raised the bar a week ago by sacking Ian Campbell for doing nothing more than the meeting, in his then-capacity as heritage minister, a delegation which included Burke.

Ever since December, when Rudd promoted him to shadow attorney-general, he has dealt the Government more grief over David Hicks than Labor did collectively over the previous five years.

[14] Thomson repeated his call to cut immigration levels in September 2009 following the release of a report indicating that the population of Australia would grow to 35 million by 2049.

Thomson said that Australia was "sleepwalking into an environmental disaster", and predicted that such a population would tend to outgrow its resources of "food, water, energy and land".

[16] This aims to stabilize Australia's population at 26 million by reducing skilled immigration and cutting the net overseas migration program to 70,000 per annum.

)[17] Kelvin Thomson describes himself as a keen environmentalist and naturalist; and as an MP he has been strongly anti-nuclear, pro sustainable population, and pro-action on climate change.

[23] In 2012 Emeritus Professor Ian Lowe, president of the Australian Conservation Foundation, examined Labor's views on population and environment in his book Bigger or Better?

Lowe argued that these were distorted by a pro-growth ideology that was in conflict with the evidence, and by a failure to understand the infrastructure costs of rapid population growth.

[27][28] Since 2008 Thomson has emerged as a political theorist, whose speeches and articles question some of the Labor Party's current directions and call for reforms.

[29] In a series of papers and speeches collected on his website,[30] Thomson argues that such rapid growth imposes high costs upon government budgets, upon natural and urban environments, and upon citizens' finances and lifestyle.

Answering those who imagine Labor could solve this problem by better planning or by allocating more funds, Thomson suggests they do not understand the crippling effect of the infrastructure costs imposed by population growth.

"[35] In a speech[36] in Parliament in March 2012 he recommended to his colleagues a paper by O'Sullivan in Economic Affairs[37] as crucial reading "for anyone who seriously wants to understand ...why governments of all persuasions struggle to meet people's needs and expectations."

[38][39] Here Thomson suggested that one reason many politicians around the world imposed policies to promote population growth was that they did not realise how likely it was to shorten their own political longevity.