Ms Bailey, who had faced a potential revolt by shareholders against her pay package, gave notice of her departure to the company’s board today.
By December she will have served almost 10 years with the company having led it through some of the most turbulent economic times in the history of the publishing industry.
Her departure triggered calls from veteran media pundit and former Mirror editor Roy Greenslade for Trinity’s national and regional divisions to be demerged.
In a statement issued last night, the group said that despite the challenging environment, she had ensured the company had continued to deliver ‘robust profits.’
Chairman Sir Ian Gibson said “The company and the board are grateful to Sly for her immense contribution and leadership over an extended period and wish her well for the future.”
Ms Bailey said “For the past ten years I have had the privilege of being CEO of Trinity Mirror plc, a fascinating and all consuming role. Newspapers are a business like no other.
“Now I feel the time has come to hand over to someone else to take up the challenge and for me to seek new challenges and opportunities elsewhere. My immediate priority is to continue to run the business, to deliver the best possible performance for 2012.”
Sir Ian will begin the search for a new chief executive immediately.
In a blog post today, Roy said whoever takes over should consider de-merging the group’s national division from its regional titles, which include the Liverpool Echo, Manchester Evening News, Birmingham Mail and Newcastle Evening Chronicle.
“Bailey never got to grips with the central contradiction of the company she inherited. There is no synergy between national newspapers and regional/local newspapers,” he writes.
“If the current Trinity board under its new chairman, David Grigson, really want to do something valuable, they should consider splitting Trinity Mirror in two.
“They should seek an owner for the national titles – possibly the three in London, if not the pair in Scotland – who is prepared to spend the necessary funds to give them one last chance at revival.
“The nationals division generates 60pc of group revenue and 79.4pc of its profit….the Mirror, given the right ownership – given love – could still offer proper competition to The Sun, especially in view of its own current problems.”
However while Roy’s proposal envisages Trinity selling the Mirror, he appears to suggest it should retain its regional titles.
“As for Trinity’s regional business, it is difficult to imagine a willing buyer just now, or at least one prepared to offer a decent sum,” he adds.
“Sly Bailey has presided over ten years of cuts and decline. She has cut the number of employees by almost a half and slashed budgets in some of the most important newspaper titles in the regions,” she said.
“There is a desperate need for a fresh start with imaginative corporate leadership committed to working in partnership with the workforce to build a growing business.
“The NUJ hopes the group’s incoming board will reject the cuts-dominated agenda that has been the characteristic of the Bailey years and show faith in quality journalism.”