Frequently, UK celebrities and politicians publish memoirs where they admit to breaking laws related to illegal substance use, yet they never seem to be prosecuted after openly admitting it. A recent example is David Cameron, the previous prime minister, which is especially interesting since during his tenor he resisted a reform of drug laws, which means many people who did nothing worse end up being prosecuted themselves.
As far as I know, UK law does not have a statute of limitations, so the fact that these crimes occurred long ago is not by itself a reason to let it go. The publication of these memoirs should provide sufficient evidence that the crime took place, or at least form the basis of an investigation.
Yes, I am aware of (Why are drug using celebrities free?) but the answers there are US specific and I'm interested in a UK perspective.