Brewer and pub group Marston's said it is continuing to see the improvement in trading that began in April in spite of recent unseasonal summer weather.At the company's managed pub division, like-for-like sales in the six weeks to August 1 were up by 2.3% from the same period the previous year, compared with a fall of 1.2% over the 43 week period.Food sales, which now account for nearly 40% of the firm's retail revenue, climbed by 6% over the six week period and by 2.2% over the 43 weeks.'Operating margin trends continue to be in line with those reported for the first half-year largely driven by tight cost controls; an easing of food input cost inflation; and the careful management of promotional offers,' it said.While cautious, Marston's, which operates more than 1,700 pubs across England and Wales, says it is confident of meeting its expectations for the year.The firm said it remains on target to raise around £20m from disposals of smaller pubs and other properties but also has plans to invest around £140m in developing about 60 new pubs. It completed a rights issue last month, successfully raising £165m.It has already started developments in Caterham, Surrey; Ashbourne, Derbyshire; and in Aylesbury, Buckinghamshire.