This story would, before the referendum, have been cited as one of the malign effects of the European Union. A multi-national company has shifted production of a popular British confection to another EU state because costs are less there. It was done by Cadbury, even before the Kraft/Molendez takeover. In that case, Poland was also involved, along with the Republic of Ireland.
Now there are fellow-Remainers who blame Brexit for the move, which seems illogical. If anything, Brexit should increase the incentive to keep sweetie production here because of the tariff barriers which would be erected. However, it could be that the York factory relies on Continental labour which would be choked off if Mrs May has her way.
There is a short history of Blue Riband on Morrisons' web pages. I had not realised it was originally as Scottish as Tunnock's tea cakes or Barr's Irn-Bru. I do recall it becoming more bland in flavour in the 1960s, which must be when Rowntree took over Gray Dunn.