The National Audit Office reported that the Department designed both ECO and the consumer protection and quality assurance system to operate at arm’s length from government, and that the Department gave itself limited oversight and influence of ECO4 and GBIS. It concluded that the Department and Ofgem took quick action but this was only after TrustMark shared its analysis of high levels of non-compliance with quality standards in external wall insulation in October 2024.56 Witnesses at our oral evidence session indicated that other information should have alerted the Department to the issues much earlier.57 The National Audit Office concluded that the Department did not fully use the levers it did have to oversee ECO4 and GBIS, and that its poor oversight of the schemes meant senior officials assumed the quality assurance system was working when it was not.58 The Department accepted that it should have been more questioning and given the schemes more oversight, and that there were not enough installation checks.59