(ShareCast News) - Daily Mirror publisher Trinity Mirror reported a jump in first-half pre-tax profit on Monday, thanks in part to its acquisition of news publisher Local World last November.In the 27 weeks ended 3 July, adjusted pre-tax profit rose to £66.9m from £47m as revenue increased to £374.7m from £288.5m, benefiting from the Local World acquisition and an additional week of trading in the period.This made up for losses from the launch of failed daily newspaper New Day, which closed on 6 May.Chief executive Simon Fox said: "I am pleased we delivered another strong performance despite the challenging print environment. We are already seeing the benefits from our acquisition of Local World last year and continue to tightly manage the cost base across the group.""Our strategic focus remains to grow digital audience and revenue whilst protecting print revenue and profit. We are confident that our strategy and our strong balance sheet position will enable continued progress despite increased uncertainty around the economic environment."Also on Monday, the company announced a share buyback of up to £10m.As far as Brexit is concerned, Trinity Mirror said it has created "increased macroeconomic uncertainty" and warned that revenues could take a hit."Whilst the impact is uncertain and hard to assess, based on current UK growth forecasts there is a risk that our revenues could be lower than expectations."At 1030 BST, Trinity shares were up 6.2% to 79.67p.