Unite national officer Steve Sibbald said that he had never seen an issue run for as long as this before, but added that the sides were so far apart that an end was nowhere in sight.

Employees took a 13% pay reduction over a year ago to help the company during the difficult financial period. Staff were on the understanding that a review would come 12 months later with a view to getting wages back up. However, nothing has been forthcoming.

In May this year, staff began striking in a bid to force the company to reverse the cuts; however there has been no movement.

Sibbald said: "We have spoken to both sides and said maybe if you move slightly the other side will move as well and we can get something running. But they are so entrenched.

"In 31 years of dealing with individual cases I have never seen anything go on this long without anything at all being resolved. This isn't a political statement, there is no other agenda, but pure and simply huge differences have developed over the past three years."