John Suffolk has announced he is to step down at the end of the year in major blow to government technology strategy.
Suffolk - ranked the fifth most influential person in UK IT - has been working on the largest overhaul of IT contracting and execution the UK government has ever experienced, in a job that is arguably one of the most challenging in the industry at the moment, with huge pressure to cut spending to the bone.
Since his appointment to the job of government CIO in summer 2006, Suffolk has been one of the key figures behind the government's G-cloud strategy and has overseen the review of all public sector IT projects and contracts, and imposed a moratorium on any new technology contracts or extensions above £1m.
Speculation had been rife in the supplier community during the summer that Suffolk resignation was imminent, but he told Computer Weekly back in August he had no plans to step down.
According to the Cabinet Office, chief operating officer for the Efficiency and Reform Group (ERG), Ian Watmore will chair the CIO council "until further notice".
"It has been a great honour to have been a civil servant and a huge privilege to have led the IT profession over the last five years. Without doubt we have transformed the UK into a leading user of technology benefiting citizens and the UK economy," Suffolk said.
"I am immensely proud of the way we have supported the new coalition government in its first six months and have greatly enjoyed working with Francis Maude and his team," he said.
"I know that with his drive and passion for delivery the very good work we have started will continue and be a great success."
Prior to being hired as government CIO, Suffolk joined the Home Office in 2004 as the director-general leading the IT transformation of the criminal justice system.