Your mixing up two different things. The European Convention on Human Rights is from the Council of Europe not the EU. The UK joined it in the 50's long before we joined the EU. In fact it was a UK lawyer who wrote most of it so a lot of it was drawn from legal notions and concepts familiar to the UK.
The Human Rights Act was passed in 1998 by Parliament when we had a Labour Government. Essentially it allowed UK citizens to go to the UK courts to have the rights enumerated in the ECHR enforced directly by UK courts rather than needing to go to the European Court of Human Rights.
The examples you give sound suspiciously like Daily Fail drivel to me but I don't know the details of those cases. No system is perfect and sometimes individual cases can throw up frustrating results. Sometimes Jurors get it wrong, in fact around 40% of the time they don't convict maybe because of innocence maybe they got it wrong. It doesn't provide a sound argument for scrapping all jury trials though.
As it happens of the cases taken against the UK government to the European Court of Human Rights around 97% don't get accepted for an oral hearing, of those the Government wins around 2.5% of the 3% heard in oral hearings. So essentially the UK government loses 0.5% of cases taken to the ECHR. That doesn't sound too onerous to me.
