By Antony Clements-Thrower Motorists have been warned ofmore expected delays on the M25 next month, as a large stretch of the infamous motorway is set to be closed. National Highways says the seven miles between junctions nine and ten will be closed both ways from 9pm on Friday May 10 until 6am on Monday May 13. The decision to shut it was made to allow concrete beams for a new bridge and gantry to be lifted into place. Drivers who need to travel will be sent on a 19-mile diversion route on the A3 and the A243. The closure is the second of five weekend closures as part of a £317 million projec…