The answer lies in the fact that Section 3 of the Human Rights Act, as also many other sections, hedges its bets by saying that, "so far as it is possible to do so", primary legislation and subordinate legislation must be read and given effect in a way which is compatible with the Convention's rights.
For instance, Section 12 of the Human Rights Act emphasises the role of courts in defending the right to freedom of expression, and states that this Section applies if a court is considering "whether to grant any relief which, if granted, might affect exercise of the Convention right to freedom of expression". (Coppel, J; "Human Rights Act 1998: Enforcing the European Convention on Human Rights in Domestic Courts"; 1999) Moreover, it is considered unlawful for a court to act in a manner contrary to a Convention right "unless obliged to act in such a way by a provision of primary legislation". (www.highbeam.com/doc/IP3-77629772.html). (www.opsi.gov.uk/acts/acts 1998/ukpga/19980042_en_1)
Incidentally, discretionary increase in police powers has landed the UK Government at least once in the soup. Article 15 of the Convention states in Para 1 that "in times of war or other public emergency threatening the life of the nation, any contracting party may take measures derogating from its obligations under the Convention to the extent strictly required by the exigencies of the situation, provided that such measures are not inconsistent with its other obligations under international law". However, in the case of Brogan and others v United Kingdom (1988; II EHRR 117) four persons were arrested on the suspicion that they were provisional members of the IRA, and detained under Section 12 of the Prevention of Terrorism Act 1984.They were released after four-to-six days. They claimed that Britain had violated several parts of the Article 5 of the Convention; for instance, Article 5, Para 1 (C) on the ground that they were not arrested on suspicion of an "offence". Furthermore, after being arrested they were not promptly either taken before a judge or released, as the provision states they should have been in Para 3 of Article 5. The court held that on all four counts there had been a violation of Article 5 of the Convention. ("Issue of Terrorism and Its Impact on Human Rights"' www.Mindrelief.net; 2007)
Additionally, there has been no consistency in the interpretation of the Human Rights Act and the European Convention on Human Rights by English courts. "Diane Pretty's attempt to challenge the Director of Public Prosecution's refusal to provide an undertaking not to prosecute her husband if he assisted her to commit suicide failed because the European Convention on Human Rights did not contain an implied right to euthanasia (R (Pretty) v DPP (2002) 1AC 800). Similarly, Human Rights Act challenge to the Hunting Act 2004 (R (Countryside Alliance v Attorney-General (2006) EWCA Civ 817) failed in part because Article 8 was not engaged. (http://webarchive.national archives.gov.uk). It has also been held that the statutory regimes relating to matters as disparate as the supply of water (Marcic v Thomas Water; 2004; 2 AC 42), regulation of solicitors' profession (Holder v Law Society; 2003; 1-WLR 1059) and preservation of embryos (Evans v Amicus Healthcare; 2005; Fam 1) are compatible with the European Conv