Royal Mail has won a high court injunction preventing the first national postal strike in a decade, which it said could have disrupted postal voting in the general election.

The Communication Workers Union (CWU) said it would appeal against the injunction after it was granted in London’s high court on Wednesday.

Trade union sources said strike action could still take place before Christmas – a key commercial period for Royal Mail – if members vote again and even if the legal appeal is lost. The strike cannot take place before the general election on 12 December, unless the appeal succeeds.

Members of the CWU overwhelmingly backed industrial action in a dispute over job security and employment terms and conditions. Last month 97% voted in favour of action, on a turnout of almost 76%. However, Royal Mail successfully argued that there were “irregularities” in the ballot.

The high court judge, Mr Justice Swift, said the CWU’s actions, including encouraging members to vote at work, amounted to “improper interference” with the ballot on strike action.

He said: “What the CWU did in this case was [...] a form of subversion of the ballot process.”

Dave Ward, the CWU general secretary, said its members were “extremely angry and bitterly disappointed” with the judgment. He also held open the option of reballoting members.

Ward described Royal Mail’s decision to seek the injunction as “a cowardly and vicious attack on its own workforce”, and said the victory would be “shortlived”.

The High Court has ruled against us. Genuinely this is an utter outrage. 110,000 workers vs the establishment.



We will be live shortly.



Stand strong. We will not be moved #WeRiseAgain 🦁 — The CWU (@CWUnews) November 13, 2019

According to government’s code of practice on industrial action, unions are required to give employers a week’s notice of their intention to ballot, after which seven days is the minimum period for members to vote. If workers back action the union must then give 14 days’ notice to the company ahead of the strike.

The price of Royal Mail shares rose by 1.4% after the judgment.

Royal Mail sought the injunction last Friday, saying it had supplied evidence from 72 sorting offices that unions breached legal obligations in holding the vote.

Shane O’Riordain, a Royal Mail managing director, said the FTSE 250 company had “no option but to resort to legal action”, and repeated an offer to reopen talks if the union committed to not striking before the end of 2019. He said the company planned to ask the union to review its internal processes.

Union members are required to vote in private at home rather than at work. Royal Mail said some workers intercepted their ballot papers at sorting offices – before they were delivered to their homes – and filmed and photographed themselves voting in favour of strike action. The CWU said Royal Mail had relied on the witness statement of one manager, and that no balloted members had complained about interference.