Staff began walking out every Friday, initially for four hours but now five, after Impact refused to discuss the possibility of increasing employees' pay on the back of a 13% reduction just over a year ago.

After 12 weeks, any industrial action has to be reballoted, so the strikes could potentially come to a close at the end of July.

However, Unite national officer Steve Sibbald said that members were planning to continue walking out.

He said: "Obviously we have been gauging the members' views ahead of a second ballot on the matter and the feedback is that they want to continue.

"We don't know how long this will continue, but there doesn't appear to be any movement from the company at this stage."