Personally, I don't like the idea of a sex offenders register. Any offender who poses a danger to the public should not be released. If that means they spend their entire life in prison, so be it.
This time the ruling came from the British Supreme Court, but the law they appealed to was not our own:
Five supreme court justices upheld a decision by the Court of Appeal that the lack of a review was incompatible with the European Convention on Human Rights, the strongest judgement they can give against a piece of legislation.This is the same convention to which John Hirst appealed for the right to vote. At the time, the Supreme Court did not exist, so after being rejected by the High Court in April 2001, Hirst took his case to the European Court of Human Rights in March 2004. Had the case been brought today, it seems likely that our Supreme Court would also have saved Hirst a trip to Strasbourg, and provided the same ruling with a veneer of domestic respectability.
According to the Supreme Court's website,
The Supreme Court is the highest court of appeal in the United Kingdom. However, The Court must give effect to directly applicable European Union law, and interpret domestic law so far as possible consistently with European Union law. It must also give effect to the rights contained in the European Convention on Human Rights.
Under the Treaty on the Functioning of the European Union (article 267), The Court must refer to the European Court of Justice (ECJ) in Luxembourg any question of European Union law, where the answer is not clear and is necessary for it to give judgment.
In giving effect to rights contained in the European Convention on Human Rights, The Court must take account of any decision of the European Court of Human Rights in Strasbourg. No national court should “without strong reason dilute or weaken the effect of the Strasbourg case law” (Lord Bingham of Cornhill in R (Ullah) v Special Adjudicator  UKHL 26).
An individual contending that his Convention rights have not been respected by a decision of a United Kingdom court (including The Supreme Court) against which he has no domestic recourse may bring a claim against the United Kingdom before the European Court of Human Rights.
Not such a supreme court after all.