In a very unexpected move, Ian Livingston, CEO of BT, the U.K.'s dominant telco, is leaving business for a job in politics.

Livingston has been poached by the government to become Minister of State for Trade and Investment. He got there by being given a place in the House of Lords, then is expected to take up the Minister role in the upper chamber of the British Parliament from December. (A Minister of State in the British system denotes a junior role mainly for supporting a more senior, front-line Cabinet member; the position is unpaid.)

Describing the telco executive as "an outstanding business leader," British Prime Minister David Cameron characterized Livingston's choice as demonstrating "the importance of this role."

"While it has been an immensely difficult decision to step down from my role at BT, it is a huge honor to be asked by the prime minister to take on this role," said Livingston in the official announcement of his appointment, adding that the government has shown "great commitment to the promotion of U.K. trade and investment," work he says he looks forward to continuing.

[ Livingston's former firm has been in government auditors' crossfire. See U.K. Auditors Slam BT Rural Broadband Project. ]

Livingston, at the helm of the £20.1 billion ($31 billion) giant for the past five years, is to be replaced as CEO by Gavin Patterson, the man currently heading BT's retail arm. The 45-year old Cambridge University graduate is expected to formally move up to that role in September.

In the role of Trade and Investment Minister, Livingston will continue the work of his predecessor, Lord Green, in trying to grow the country's exports and attracting further investment from overseas, the government said.

"Ian has done a tremendous job in transforming BT," commented BT chairman Sir Michael Rake. "His decision to accept a government post demonstrates the sense of public service which many of us know to be characteristic," he added, before saying Livingston "leaves behind him a very capable team, one which will take forward the strategy that has served BT well and which lays out the path to further success."

"I am immensely proud to have led this company over the last five years," said Livingston, claiming that BT has made huge progress over the last few years, "but I know there is still so much more that BT can and will do."