The deal will make Trinity Mirror the biggest publisher of regional and local newspapers in the UK, with 30 per cent of the market in circulation terms and 120 million monthly unique browsers.
Trinity Mirror Solutions already handles Local World’s national print sales. However, it is too early to say whether the two groups will merge their local ad teams or if Local World will continue with 1XL, its digital ad sales platform, with rival publishers.
City sources said Trinity Mirror still has an appetite and the balance sheet to buy Express Newspapers from Richard Desmond after talks began in the spring.
Express Newspapers’ pension deficit has fallen by a third to £52.8 million, easing the way for a possible sale.
Observers suggested Desmond may consider a joint venture or another proactive move as he has a substantial war chest following the £463 million sale of Channel 5 to Viacom last year.
The Mirror released a campaign called "don’t say stupid" earlier this year. It was created by Quiet Storm.