Pinsent Masons has signed a new partnership with E.ON winning the firm a role as sole legal adviser to the energy giant's UK business.

The five-year arrangement follows a similar deal the firm struck in March with Balfour Beatty, in which Pinsents agreed to provide the construction company with day-to-day legal on an exclusive basis.

The new deal involves Pinsents providing the full range of legal services, thereby becoming E.ON's single external legal advisers in the UK.

While E.ON's in-house UK legal team will continue to carry out much of the company's work, the German-headquartered company will retain separate external advisers to the central legal function, based in Duesseldorf.

Specialist legal teams, such as London-based E.ON Exploration and Production, will also retain separate panels, which will include a small number of UK firms.

"This is an exciting and innovative partnership, not to mention a first in the UK energy sector," commented Graham Line, E.ON UK's head of UK legal.

"The legal function at E.ON has a prominent role to play in ensuring that our customers are treated fairly, and giving the business confidence as it makes infrastructure investments that are helping to keep the lights on now and in the future.

"We want to deliver a high-quality, high-value service to the business, and Pinsent Masons demonstrated through their approach and knowledge of the sector that they are the right partner to achieve that."

Pinsents' lead client relationship partner Jonathan Fortnam added: "This arrangement will allow us to support [E.ON] through the provision of a broad spectrum of specialist legal services, and give us the ability to develop the type of long-term, sustainable relationship that is key to true partnership."

Pinsents' head of client operations Richard Masters said: "We recognise that innovation is about more than finding ways to make an old model fit the new world, and are delighted that several of our clients have responded positively to our proposals to move the emphasis firmly away from the billable hour."

E.ON employs around 12,000 people throughout the UK, supplying power and gas to 5 million customers.