About 7,000 British Gas engineers staged 44 days of strike action after the company threatened to sack them if they didn’t sign up to “detrimental changes” to their terms and conditions.

The strikes led to a backlog of millions of customers waiting for planned service visits and hundreds of thousands having to wait for emergency repairs.

In the end, almost 500 workers were dismissed. But GMB says the dispute is now over after workers agreed a new pay deal with a ratio of three to one.

After “gruelling negotiations”, the union says the new deal offers improvements to overtime rates and unsocial hours payments, places limits on the amount of unsocial working undertaken, reverses the decision to close the defined benefit pension scheme to new starters and opens the door for those who left the business to return.

Andy Prendergast, GMB national secretary, said: “GMB Union will never forget British Gas’s unnecessary and cavalier actions over the past six months. But this new agreement does provide a way forward.

“We have listened to what our members wanted and have been able to deliver the improvements necessary to bring this dispute to an end. As a result of the deal, members will see significant improvements to their work life balance and will get a little bit more in the process.

“We have also kept the pension scheme open to new starters in the old service and repair division and crucially left the door open for those who were sacked to come back should they wish to do so.

“None of this would have been possible without the tremendous sacrifice of our members who should be commended for the stand they took. They have turned the practice of fire and rehire into a national issue and we will continue the campaign they started until this appalling practice is banned.”

A Centrica spokesperson said: “We’re pleased that today’s agreement with our trade unions effectively brings the dispute with GMB to an end.

“Our customers and our people are our priority and our unions are a critical partner to ensuring our business is sustainable, competitive, and set up for growth. Creating a flexible model for our colleagues and ensuring our people have the skills needed for the future is the common ground that unites us.”