London's blue-chips are set to open modestly lower, with the Footsie predicted to open around 10 points lower, which would, at least, mean it remains above the 6,000 level, having closed at 6,108 last night.Tullow Oil enjoyed record revenues in the first half of the year while achieving a 79% exploration and appraisal success rate. Total revenue for the first half of 2011 is expected to be a record for the company at around $1.05bn, compared with $486m for the same period in 2010. House builder Persimmon said market conditions in the first half of the year have been stable. The group completed 4,439 homes, down from 4,657 in the first half of last year, with saless improving from the lower sales order book at the start of the year.Tom Drury, the chief executive of waste management company Shanks is leaving the company to work closer to his home in Cheshire, the company has said.--jh