One of Britain’s largest microchip plants is facing potential closure after Apple pulled the plug on a lucrative supply deal.Accounts filed by the US semiconductor company Coherent, which owns a 310,000 sq ft facility in County Durham, revealed that the loss of its main customer had put the factory’s future in jeopardy.The Sunday Telegraph understands that the plant manufactures components for Apple that feature in the iPhone’s Face ID recognition system, but that the US giant is believed to hav...