It's theft, pure and simple
Copyright isn't a "right" in any sense of the word: it is a balance set by society to encourage people to produce intellectual property. The role of the government should be to set copyright to its welfare-maximising level (i.e., the term that generates the biggest benefit to society), not to reward to the creators at the expense of everybody else. Economic research suggests that a term of around 15 years from creation is best. Therefore, the law should be that copyright runs for 15 years, with no exceptions, and if Cliff Richard is on his upper then he can go and get a job like the rest of us.
Retrospectively _increasing_ copyright is a pure and simple theft from the public domain, and the lobbyists who called for it (e.g., the BPI) should be arrested for conspiracy. The _only_ people who will benefit from this are some record company shareholders (e.g., Citi) and a very small number of rich artists. Everyone else will lose out.