Royal Mail workers have voted massively in favour of strikes in a dispute over job security and employment terms and conditions, raising the threat of industrial action in the run-up to Christmas.
Members of the Communication Workers Union (CWU) backed action by 97% in a huge turnout of almost 76%.
The union said the prospect of the first national postal strike in a decade now “looms large”.
Around 110,000 members of the CWU were balloted in the dispute.
The CWU says that Royal Mail is not sticking to an agreement reached last year covering a wide range of issues, including plans to reduce the working week, as well as job security.
Industrial relations at the company have worsened this year, with widespread unofficial strikes breaking out virtually every week.
Terry Pullinger, the CWU’s deputy general secretary, said the union and its members were facing the “fight of our lives”.
“We face an assault on our terms, conditions and national agreements like we have never seen before,” he said.
The CWU said the result represents the largest yes vote for national industrial action since the passing of the Trade union Act 2016.
Pullinger said: “Just over one year ago the Royal Mail Group Board and the CWU agreed a blue print agreement for the future, a progressive agreement that included an historic pension solution, a mutual interest driven relationship and a joint vision for a successful postal service with social aims.
“Today the new RMG leadership are breaking that agreement.
“Our members take honour seriously and have voted to fight for that agreement against those who now seek to break up the great British Postal service in the interest of fast track profit and greed.
“Integrity and pride still matters and we will not stand aside and see what we have spent our working lives building destroyed.”
General Secretary Dave Ward said: “This result sends a clear message to Royal Mail Group – our members will not stand by as you rip up their terms and conditions and destroy the service they give to the public and businesses of the UK.
“We would urge Royal Mail Group to now enter serious negotiations with this union. We also call on the public to get behind this dispute and your postal workers.
“We are very proud of our members today. They have stood by their union in record numbers and given hope to workers across the nation.”
Ward added that Royal Mail chief executive Rico Back should now consider his position following the “historic” vote.
The union’s executive will decide the next move, but Ward said: “We will look at what gives us the most leverage.”
He said the union and its members were defending the postal service as well as their jobs.
A mediation process already in place ends on Friday, then there are three weeks before a “parting of the waves”.
Ahead of the vote, Shane O’Riordain, the Royal Mail’s managing director of regulation and corporate affairs, said there were no grounds for industrial action.
He said: “We remain committed to open and constructive engagement with the CWU. We all want a successful and sustainable company that provides good quality jobs, fairness in workloads, and continues delivering a sustainable Universal Service.
“No industrial action can be taken before the conclusion of our mediation period. We will continue to engage in the agreed dispute resolution processes set out in the Agenda for Growth.
“Industrial action – or the threat of it – undermines the trust of our customers. It makes it harder for Royal Mail to pay for the existing industry-leading terms and conditions it provides.”
He said Royal Mail was honouring the 2018 agreement. Since it was put in place there have been two pay increases of 5% and 2%, the working week has been cut by an hour, and the company was working with the CWU to lobby the government for a new pension scheme.
He added: “We have announced a transformation plan, through which we want to invest £1.8 billion over five years to return our UK business to growth. Hardly any UK companies are making that kind of investment right now.”