Gerald de Cruz's association with the labour movement involved his friendship with C.V. Devan Nair during the MDU years. Nair, who was a teacher at St. Andrew's School, was impressed by P.V. Sharma and became his assistant in the Singapore Teachers’ Union. Nair asked de Cruz whether he should go into politics or into the trade union movement. De Cruz suggested that he consider devoting himself full-time to trade unions. But the friendship between the two took off only in the 1970s, when Nair was modernizing the labour movement as chief of the National Trades Union Congress (NTUC). In his work and personal relationships, de Cruz said, Nair was an extremely efficient and inspiring person, a very generous and compassionate man. De Cruz admired his tremendous courage when he finally took a stand and stood beside Lee Kuan Yew against his former comrades like Lim Chin Siong and developed the trade union movement. De Cruz steered clear of this battle, but he came back into the picture when the unions had begun to work in partnership with the government and the management to build a new Singapore. De Cruz, who chaired the NTUC's information and publicity committee, helped with the modernization movement and was awarded a gold medal by the NTUC in 1970 for his efforts as a friend of labour. Later, he became the assistant editor of Perjuangan, the monthly journal of the NTUC, which he actually edited because the official editor was not a journalist. He also helped to edit the periodicals of the Singapore Industrial Labour Organization (SILO), the Pioneer Industries Employees’ Union (PIEU), and the Consumer Association of Singapore (CASE).

However, it was not only his journalistic skills that de Cruz brought with him to his work for the NTUC. His political instincts, honed during both his communist years and during his time at the Political Study Centre, enabled him to view labour issues in the light of broader social interests.

This is seen in his contribution to the NTUC's Seminar on the Modernization of the Labour Movement, held in November 1969. The times were dire. The British had announced in 1968 that they would withdraw their military forces from Singapore.