The publisher, which bought regional press rival Local World for £220m at the end of 2015, has now embarked on a fresh round of industry consolidation by purchasing Richard Desmond’s Northern & Shell group.
It means the Labour-supporting Daily Mirror and the Daily Express, which has backed UKIP at recent elections, will now come together in the same stable.
However Trinity Mirror chief executive Simon Fox has insisted that the editorial stance of the two titles will not be compromised by the deal, citing the independence its regional titles as proof.
Mr Fox told BBC Radio 4’s Today Programme: “We have more than 100 newspaper brands, and editorial decisions are entirely left in the hands of the editors.
“The Daily Express is not going to become left-wing, the Daily Mirror is not going to become right-wing”.
Although Mr Fox admitted there would be job cuts to remove “duplication” – such as only sending one reporter to cover football matches – he insisted that the political teams of each newspaper in the enlarged group would not be “mixing in any way.”
In the same interview he also said that Trinity Mirror does not intend to close any local titles in the next year, although it closed several in 2017 including Bedfordshire on Sunday, the Bristol Observer and the Surrey & Hants Star Courier.
TM’s purchase of LW had already made it the biggest regional publisher in the UK, but the latest deal gives the company near-parity on the national stage with Rupert Murdoch’s News UK and Daily Mail owner DMGT.
It is likely that the industry regulator, the Competition and Markets Authority, will force the two companies to remain separate for up to a year to assess the impact on the wider newspaper market.
The £127m deal is only £2m more than Mr Desmond originally paid for the Express titles when he bought them from Lord Hollick in 2000.
It is made up of an immediate cash payment to Mr Desmond of £47.7m, a further £59m to be paid between 2020 and 2023, and a 10pc shareholding in the enlarged company worth £20m.
Mr Fox said: “This deal is a really exciting moment in Trinity Mirror’s history, combining some of the most iconic titles in the UK media industry. It is good for our readers, good for our customers and good for our shareholders.
“Northern and Shell’s titles have a large and loyal readership, a growing digital presence and a stable revenue mix and offer an excellent fit with Trinity Mirror.”
Mr Desmond added: “The Express Newspapers and our celebrity magazine titles have been a key part of the Northern & Shell portfolio for many years, and I am immensely proud of building them into one of the largest newspaper and magazine groups in the UK.
“Today’s transformational transaction is a logical and natural next step in the evolution and consolidation of the media sector and will create a larger and stronger platform serving all stakeholders. In Trinity Mirror we have a great partner and I am delighted to be able to retain an ongoing interest in the combined group.”
In a statement to the Stock Exchange, Trinity Mirror said there was a “strong strategic rationale” for the deal.
It said the acquisition would enable the enlarged group to widen the breadth of its editorial coverage by content sharing and provide advertisers and agencies with a combined digital audience of 234m.
It expects to deliver £20m in “annualised cost synergies” by 2020, with a significant amount of these savings set to be achieved in 2019.
In a separate trading update covering the 52 weeks up to the end of December 2017, also published today, TM said overall revenues had fallen 9pc last year.
The National Union of Journalists has already warned that the “brilliant journalists” on the Mirror and Express newspapers must not be casualties of the takeover deal.
General secretary Michelle Stanistreet said: “After many years of under-investment and one pay increase in the past decade, journalists working for Richard Desmond have been desperate for a new owner to provide the resources needed to help increase the readership and the success of the titles.
“However, the NUJ is concerned that Trinity Mirror, with its long record of making cuts to its newspapers, will not be the knight on the white horse they were hoping for.
“Therefore we will be seeking guarantees that the deal will not result in redundancies and that the titles will be able to thrive. We expect to be involved fully in consultations on the changes planned for these titles.”