Earlier in the month the union reacted angrily after E.ON revealed the new redundancy terms and days later announced the closure of the company’s Wherstead Park site near Ipswich with the loss of 330 jobs.

Following discussions with senior management Prospect has received commitments from E.ON that it will fully consult on any future redundancy terms, and guarantees relating to the staff covered by Wherstead’s closure, instead of imposing new terms as originally intended.

Prospect assistant general secretary Mike Clancy said it was evidence of what can be gained by negotiation between the company and the union where the concerns of both can be addressed.

"By reacting quickly to our members’ concerns and dealing directly with senior company officials we have been able to address the issues and prevent the situation deteriorating."

Negotiator Richard Hardy said: "Our members were very angry that E.ON had acted unilaterally to reduce their redundancy pay, resulting in the loss of thousands of pounds. For members at Wherstead Park this was a double blow.

"But it is a credit to them and an example of the relevance of unions in today’s workplaces, that this anger was channelled into resolving their grievances through negotiation, successfully influencing the company’s approach for the future."