According to the union, 93% of members said they opposed Royal Mail privatisation, 95% supported the CWU’s rejection of Parcelforce’s pension proposal and 96% supported CWU’s pay claim.

The ballot results were broadly in line with the results of the consultative ballot of Royal Mail workers held in June. More than 90% of Parcelforce's staff are CWU members, and the ballot achieved a 72% turnout.

Dave Ward, CWU deputy general secretary, said: "Workers in Parcelforce have spoken loud and clear and added their voices to those of hundreds of thousands of others – they are against Royal Mail privatisation.

"There is a consistent message from both the workforce and the public that privatisation is not needed, not supported and not popular. It’s time the government looked at alternatives to privatisation – something we can help them with."

June’s Royal Mail consultative ballot proved to be a pre-cursor to a full national strike ballot at the letters operation by the CWU, which is due to be held next month.

However, Parcelforce is a separate company, although wholly owned by Royal Mail, and as such is subject to separate negotiations between the union and management.

Open ended talks between the union and Parcelforce management are on going and a ballot on strike action can only be held if no agreement is reached on pay and conditions. It would be illegal for Parcelforce staff to strike purely in protest against privation of the Royal Mail.

"Nothing’s been ruled out at the moment, but there are no imminent indications talks will fail, but we still have no pay deal in place for this year," said a CWU spokeswoman.