CMS partner and former energy sector head, Robert Lane, has died, the firm announced on Tuesday.

Lane, who was 61, was a partner at the firm in the U.K. for over 30 years. He also sat on the firm's council. The firm did not provide details on the cause of death but a spokesperson said it was "sudden and unexpected".

Lane originally joined CMS in 1988 from Slaughter and May. He also founded the firm's energy group, a practice which he led for two decades.

In Her Majesty's Birthday Honours in 2001, he was awarded a CBE for services to British commercial and legal interests overseas.

In a statement, CMS senior partner Penelope Warne commented: "We will always remember Robert for his immense technical knowledge of the nuts and bolts of all aspects of the power system, his attention to detail and his extraordinarily high standards of client care, for all of which he had a huge passion.

"But we also remember him as a man of great warmth who was just as excited by the achievements of his team, and supporting the growth of the CMS family around the world."

During his career, Lane served in a number of energy and governmental associations including the UK Government's Power Sector Advisory Group, The Parliamentary Group for Energy Studies, The British Electricity Association, The Energy Industries Club, The Energy Committee of the City of London Solicitors Company and the Nuclear Industry Association.