[6] After losing his job when bus conductors were phased out of London life in the 1980s, Turner became active in the T&G's education programme, studied for an MA in Industrial Relations from Keele University and taught local and national shop steward and activist training courses.

[8][9] In 2011 Turner became Director of Executive Policy for Unite the union, which had been formed in 2007 as a result of a merger between the T&G and Amicus, before being appointed to Assistant General Secretary in 2013.

He fought against the Transatlantic Trade and Investment Partnership (TTIP)[12] and changes to the social security system, particularly the Bedroom Tax, calling it 'ideologically bankrupt'.

He was particularly prominent in the 2017/18 successful campaign to defend jobs at Bombardier in Belfast, during the firm's bitter dispute with Boeing, leading a delegation of Unite workers to Washington and Montreal.

[14] He played a key role in the battle to save the iconic Harland and Wolff [15] shipyard in Belfast after the government and the company said it didn't have a future and, in 2021, he led Unite's negotiations with the senior management team of Rolls-Royce to secure its factory in Barnoldswick, Lancashire, and prevent hundreds of job losses.