Wren - who took up the post this week - replaces Pam Teare, who was a key witness in the Hutton Inquiry and author of the controversial Q&A briefing that lead to the naming of Dr David Kelly. Teare joined the Crown Prosecution Service in March (PRWeek, 25 February).
Dogged by the country's interminable travel problems, the DfT has recently been criticised for dissolving the Strategic Rail Authority, which cost £250m to set up.
Wren heads a 40-strong press office and reports to acting director-general of media and communications John Pitt-Brooke.
He leaves the DfT devoid of a comms director or a head of news. He has been acting comms director since Charles Skinner joined Haringey London Borough Council as head of comms in November.