The Metronet chairman is being replaced by Graham Pimlott who will take up the post on 9 January

Keith Clarke has stepped down as chairman of Metronet just weeks after saying he would not be leaving the post in the near future.

Clarke, who has been the Tube consortium’s non-executive chairman since April 2005, will be replaced by Graham Pimlott on 9 January.

Pimlott is the chairman of the Export Credit Guarantee Department (ECGD), the UK’s export credit agency, and Tilney Group, a wealth management business.

Last month, Metronet said that Clarke would be replaced sometime in the future. It was thought his departure was linked to a report from PPP arbiter Chris Bolt, which stated that Metronet was significantly behind schedule in its work on stations. The Tube consortium denies this.

Clarke, who is also the chief executive of consultant WS Atkins, said: “I am delighted that Graham is joining as I believe that his wealth of board experience in both the private and public sectors will be enormously valuable to Metronet.”

Commenting on his appointment, Graham Pimlott said: “Metronet has a complex but essential job to renew a large proportion of the Underground's infrastructure. I relish this challenge and look forward to working with Andrew Lezala and the management team in the task, which is important to so many Londoners.”

Lezala, the chief Executive of Metronet, said: “We welcome Graham Pimlott to the Metronet team and look forward to working with him, as we move forward with the many challenges of rebuilding the Tube – the world's largest metro regeneration project.”