Costain and National Grid agreed to part ways in 2020 more than halfway through the £113m upgrades following significant changes in scope to the project.

Under a range of scenarios Costain initially said it would either collect £50m or pay out more than £57m.

But two month ago, Costain announced it would be due to make a payment to National Grid of up to £53.5m, after several adjudication decisions.

The legacy contract has now finally been settled with a £43.4m payment to National Grid.

In a statement this morning Costain said: “The settlement agreement brings an end to the dispute after the contract was mutually terminated in June 2020 and prevents any further claims under the contract.

“We are focused on delivering our strategy to transform the business, reduce risk and improve returns.

“We have made a good start to the new financial year and, with the UK Government’s significant investment in infrastructure, we look forward to the future with confidence.”