JISC has released Preservation of Web Resources.
Here's an excerpt:
There are institutional benefits to preserving web resources. Considerable time and money has been invested in the creation of digital outputs and content, and in their storage and maintenance. Although there are costs associated with launching a web preservation programme, it’s also money wasted if resources aren’t preserved. Institutions have responsibilities to: students and staff, who may make serious choices about their academic careers based on website information; and researchers and scholars, who may need to use the university’s resources in the future. Ensuring that the wider community has long-term access to research materials will be broadly beneficial.
There is also the matter of protecting institutions. Many risks are faced by organisations that choose to ignore web preservation. An institutional record may be required for the checking of strategic, legal, financial and contractual information, or simply for the day to day continued efficient running of the organisation. But there are external threats too. These include: data loss; loss of records and loss of resources; a failure to be information compliant (through not meeting Freedom of Information requests); risks of breaching copyright; and even risk of litigation from students or the public. Consider if a legal action were brought against an institution as a result of certain information that was exposed two years ago, and has since been taken down. Could the institution provide evidence, such as an audit trail, in court?