The designs of high-value, long-life products such as aircraft, trains and industrial plant continually evolve, both at the time of manufacture but also during their operating lives. Such products are invariably managed in complex multi-stakeholder environments where the product change process spans a number of organisations. It is clearly important that regulatory systems are able to monitor that the design integrity established when a product is first created is maintained through-life. The purpose of this paper is to assess the challenges to maintaining design integrity throughout the product lifecycle. Discussions with a number of organisations undertaken by the authors have indicated that managing product information in the context of the product change process continues to be problematic. There is a fundamental need to improve the alignment between through-life design management processes, information technology and the management models used to guide decision making. To quantify the challenges currently being experienced a mathematical model has been developed to support investigations into the level and impact of design changes that have been reported by engineers in industry.