On 6 April 2015, the crew of an A320 under radar control in Class E airspace and approaching 4000 feet made a very late sighting of a glider being flown by a student pilot which appeared ahead at a similar altitude. The glider pilot reported having seen a 'cone of light' coming towards him. Both aircraft took avoiding action as practicable and passed within a recorded 450 metres with the A320 passing an estimated 250 feet over the glider. The glider was not fitted with a transponder and was not required to be, and the controller had only secondary radar.