In a branch vote, 18,025 members of the Public and Commercial Services (PCS) union backed staying neutral, while 5,075 voted for the Yes position. There were no votes for the No position.
The result came despite a personal plea from deputy first minister Nicola Sturgeon at yesterday’s consultative conference in Glasgow for branch delegates.
Last night, insiders said Yes campaigners, who had been confident of success, had been outmanoeuvred by No supporters who swung behind the neutral option.
The union will now adopt an “active engagement” campaign under the banner “PCS informs – you decide”.
The outcome of the vote will be considered by the PCS National Executive Committee, with any final decision to be taken by the annual delegate conference in May.
Janice Godrich, PCS national president and chair of the conference, said: “Today we’ve seen PCS members present thoughtful, balanced arguments weighing up the pros and cons of the way forward. Today does not mean sitting on the fence.”
Sturgeon made the bid for a Yes vote, stating that Scotland could be a “progressive beacon” under independence. “Right now the UK is one of the most unequal societies in the developed world,” she said. “I can guarantee you that we will protect your terms and conditions and pensions.
Labour MSP Neil Findlay at the conference for the No side, said he rejected the “counsel of despair” that Britain would never change.
He said:“I want political change to improve the lives of people from Shetland to Dorset, from Cardiff to Belfast. That is the solidarity the movement was founded on, and should continue to build.”