[1] After returning from the United Kingdom in 1978, Leung joined the New Youth Study Society, a labour school founded by activist Lau Shan-ching in Tsuen Wan, as a lecturer.

[4] In 2010, Leung was invited to participate in the establishment of a pro-labour party, along with ex-Civic legislator Fernando Cheung, Confederation of Trade Unions' Lee Cheuk-yan and Civic Act-up's Cyd Ho.

[12] On 12 October 2016, Leung was granted the authority to chair a Legislative Council meeting for the election of the new president, due to having the second highest seniority after presidential candidate James To.

[13][14] The meeting concluded with pro-establishment candidate Andrew Leung elected as President of the Legislative Council of Hong Kong in a 38–0 vote.

[15] On 19 June 2020, Leung announced his plans to contest the 2020 Hong Kong legislative election as the second candidate behind NWSC chairman Lo Ngai-yin.

[3] A fictional retelling of his contributions was depicted in a Hong Kong movie, titled From the Queen to the Chief Executive, released in 2001.

[22] In the memoir, solicitor and former actress Mary Jean Reimer described Leung's advocacy towards the disadvantaged and socially vulnerable groups.

[23] Leung's arrest was made on the claim that he participated in an unauthorized assembly on 18 August 2019 amid the anti-extradition bill protests.

[24][25] In December 2021, Leung was sentenced, together with seven fellow activists, for illegal assembly over his participation in the 2020 Tiananmen vigil in Hong Kong, and for having "incited" the public to join them.