Unite general secretary Len McCluskey has warned against focusing on the City's needs and wants in Brexit negotiations and neglecting the country's "manufacturing heartlands".
The union boss is also ramping up pressure on the government to deliver more concrete assurances on defending the UK car industry in Brexit negotiations.
“There are almost one million UK workers engaged in building nearly two million vehicles every year," he said. "This industry contributes billions to the Treasury and provides decent jobs for our communities."
McCluskey warned against prioritising the City above all else in the talks, due to start when Theresa May triggers Article 50 on 29 March.
A ‘bad’ Brexit will put this at risk. We cannot have a Brexit that suits the City of London, but neglects our manufacturing heartlands because that is to consign these communities to a poorer future.
The money our members earn is spent in their communities, supporting other local jobs and services. Sadly, this cannot always be said for the financial high rollers.
McCluskey called on the Prime Minister to "make it abundantly clear to manufacturing workers and our auto employers that their futures are your priority" by stating definitively that she will be "seeking access to a barrier-free Single Market and the customs union".
Yesterday, the SMMT revealed that UK car manufacturing had recorded its biggest February in 17 years, driven by overseas demand, and repeated the importance of avoiding "barriers to trade", whether tariff, customs, or other regulatory barriers.
The government has said it will pursue "a bold and ambitious trade agreement" with the European Union, that should allow for the "freest possible trade in goods and services". But there has been uncertainty across the automotive sector as to how this will play out.