Trinity Mirror said in a statement that Walker was "planning to reduce his commitments to some extent", but that "he hopes to remain involved in the newspaper industry on a consultancy basis."

In the statement, Trinity Mirror chief executive Sly Bailey said: "Norman has played a key role in our business over many years. I thank him for his enormous contribution to the group, and wish him well in the future."

His departure follows a shake-up in the Trinity Mirror print operation that has taken place since Bailey's appointment as chief executive in February 2003.

In March, it emerged that a group manufacturing division at Trinity Mirror had been created, headed by former West Ferry Printers managing director Rupert Middleton.

It is understood that Middleton's brief is to exploit the potential synergies and savings from making the 12 national and regional print sites work together.

The newspaper publisher also recently reviewed its two print sites in Scotland, saying that it wanted to match capacity with demand.

Walker first joined Trinity Mirror in 1981. He held a number of roles on newspapers including the Kenya Times and the Glaswegian before becoming managing director of Mirror Colour Print in 1998. He oversaw the Watford, Oldham and Cardonald plants. Walker was unavailable for comment as PrintWeek went to press.

Story by Josh Brooks