London's leading shares are set to start the week on a dull note with City traders predicting the Footsie will tumble back below the 5,700 mark, down by around 50 points.Temporary power and temperature control provider Aggreko saw an acceleration in the rate of underlying growth in the second quarter. The group now expects that revenue in constant currency and excluding pass-through fuel in the first half of 2011 will be about 9% higher than in the corresponding period of 2010.Power systems colossus Rolls-Royce has bagged the contract to provide engines for an enhanced version of the Airbus A350-1000 aircraft.Trendy sportswear retailer JD Sports Fashion has gained a foothold in Spain with the acquisition of the businesses of Sprinter, a sports chain operating in the south of the country.--jh