Cortes was born and raised in Gibraltar; while growing up, he never spoke English with his family.[2] He left school with no qualifications.[3]
He became an apprenticeelectrician, joined a local union, and gained technical qualifications from the Gibraltar and Dockyard Technical College. It allowed him to pursue further studies at a technical college in Kent. He studied Engineering at Heriot-Watt University, later becoming a full-time student representative. Later he would gain master's degrees in Optical Electronics and Business Economics from the University of Strathclyde.
In March 1998, Cortes joined the TSSA, the UK's second-largest rail union, which was formerly known as the Railway Clerks' Association, a white-collar union. On 15 November 2011, he was elected General Secretary for a five-year term. In December 2016, he was re-elected with 66% of the vote on a turnout of 19%.[4]
In 2022, Cortes was accused of sexual harassment by a former TSSA employee, something which he vehemently denied and which had not been upheld after an internal investigation.[6]
In February 2023, the report of an investigation by a Labour Party member of the House of Lords that was requested by the Trade Unions Congress (TUC) was published.[7] The report was critical of Cortes and other senior TSSA officials and supported the harassment allegations made by several former TSSA staff. Cortes and several other senior TSSA staff were dismissed following publication of the report commissioned by the TUC.[8]
In June 2023, delegates at the TSSA annual conference rejected appeals from former General Secretary, Manuel Cortes, and former Interim Organising Director, Luke Chester, after they were both dismissed for gross misconduct. Delegates heard from Cortes and Chester by video link during a closed session of the gathering in Cork, Ireland. During his appeal, Cortes removed his shirt and argued he had been "made a scapegoat". The decision means that conference has upheld the dismissals of Cortes and Chester.[9]