Article 8 of the European Convention of Human Rights (given effect in the UK by the Human Rights Act 1998), gives people the right to a private life, family life, home and correspondence.
This right means that public authorities are not allowed to interfere with a person’s privacy, for example, by disclosing their personal information, unless it is lawful, necessary (in the public interest) and is for a legitimate purpose such as public safety; protection of health or morals; rights and freedoms of others and prevention of disorder or crime. Public interest in making the disclosure must outweigh the individual’s right to a private life.
If you want to share personal information for any of these broad purposes (even without the person’s consent) you will not breach that right as long as your disclosure is proportionate, relevant and necessary.
In practice, it is recognised by the courts that if you comply with the Data Protection Act rules, sharing will be lawful and will not breach this right.