Britain’s oldest nuclear plant closed on Wednesday, leaving in its wake a £700m decommissioning bill and further questions about the UK’s ability to keep the lights on. The closure of the Wylfa plant in Wales after 44 years of service puts more pressure on EDF Energy to take a final investment decision for new reactors at Hinkley in Somerset. The station on the island of Anglesey generated enough electricity to power 1m homes, and with a capacity of 1,000MW was once the largest facility of its kind in the world. But after an earlier life extension scheme expired, the last of the 26 British-designed Magnox reactors was switched off by the private consor tium that manages the plant for the Nuclear Decommissioning Authority (NDA). The site was due to close in 2010 but it was kept open for a further five years as fears mounted that Britain would face an electricity shortage because new atomic and gas-fired power plants were not being constructed. “Wylfa has been a terrific success story for Anglesey and the UK nuclear industry. We have generated safely and securely for many years, which is an excellent achievement,” said Stuart Law, the site director.