Post Office workers are to stage five days of strikes next week in a dispute over jobs, pensions and branch closures.
The Communication Workers Union said the action will include Christmas Eve.
It will affect main branch Post Offices such as Huddersfield’s Northumberland Street branch.
The union is embroiled in a long-running dispute over job losses, the closure of a final salary pension scheme and the franchising of Crown Post Offices, the larger branches usually sited on high streets.
CWU general secretary Dave Ward said: “Our members are being forced into fighting to save their jobs and this great institution from terminal decline. We didn’t want to be in this position, but unless we stand up now, the Post Office as we know it will cease to exist.”
Kevin Gilliland, the Post Office’s network and sales director, said: “We are extremely disappointed that they prefer to resort to calls for strike action. Our focus must be on supporting our customers who rely on us at Christmas more than ever.
“We want to reassure customers that if further strike action takes place next week at least 97% of our 11,600 branches will not be involved. It will be business as usual in almost all of our network, with over 50,000 Post Office people on hand to support customers as they make their preparations for Christmas.”