'These rights are protected by Article 8 of the European Convention on Human Rights forms part of UK law, thanks to the Human Rights Act 1998.
According to the European Court of Human Rights, private life is a broad concept that does not stop at the door of the workplace. For example, under the Convention:
Workers have a reasonable expectation of privacy when using the phone at work, especially if employees have not been warned them their telephone might be bugged
5 Monitoring of work emails can breach employees’ rights to privacy, particularly where employers do not have a workplace policy.
6 Employers must be able to justify surveillance of employee communications, especially if this involves reading employees’ private emails or online messaging. They should also explore any less intrusive alternatives
7 Covert surveillance at work can only be justified in exceptional circumstances
8 Monitoring email, internet and phone use
Employers have no legal obligation to allow staff to use the phone, email or internet at work for personal reasons. However, good employers trust staff with some private use during working hours, as long as it does not interfere with their work.
To comply with data protection rules, employers must tell staff of any plans to monitor email or internet use and the reasons for doing so. Employees should have a clear understanding of when monitoring will take place, why information is being gathered and how it will be used. ''
from www.tuc.org.uk/research-analysis/reports/i%E2%80%99ll-be-watching-you?page=5