Stuart Okin, the public face of Microsoft UK's security work, has resigned from the software giant.
In an email sent by Okin on Wednesday afternoon and seen by ZDNet UK, he revealed he was "moving on to pastures new" after eight years at Microsoft.
When contacted by ZDNet UK, he said that the transition was "just a career move".
"I'm very excited about the move. Part of the role will be to help build up Microsoft security infrastructure at Accenture."
Okin was appointed as Microsoft UK's first chief security officer in February 2002, and is well respected by security professionals.
"This should definitely be seen as a positive move for Stuart's ability and ambition," said Simon Perry, vice-president of security strategy at Computer Associates.
"It should also be seen as a show of initiative for Accenture and not interpreted as Microsoft backing off from their security initiatives in any way."
During Okin's time at the helm Microsoft has been under growing pressure and criticism for the state of some of its software, especially Internet Explorer.
Okin's shoes will be partially filled by Nick McGrath, Microsoft's head of platform strategy, who will now become the "security orchestration lead", according to Okin's email.
McGrath told ZDNet UK that Okin was moving to become an associate partner at Accenture, the management consultancy firm.
"This is an incredibly good move for Stuart, and I'm incredibly pleased for him," said McGrath, adding that Okin will be continuing his security work at Accenture.
Yesterday Microsoft admitted that a further 22 flaws had been found in its Office software. Despite this, McGrath believes that the security battle can be won.
"The security challenge facing the industry is the same for all software products," insisted McGrath.