Indeed, %SLFguy, your post is 100% false (pretty much).
For businesses based in the UK, and I assume BT is, then the Lawful Business Practice Regulations (
http://www.legislation.gov.uk/uksi/2...0002699_en.pdf) will apply. Basically, these mean that monitoring of communications over *his* infrastructure, by your employer, is perfectly legal, so long as he has told you he is doing so.
As to the ECHR rulings about the right to privacy of communications, whilst that is true, and it does mean that your employer must allow you the opportunity to make such private communications, it *doesn't* mean that *he* has to provide you with the means to do so...
[Ob. disclaimer: IANAL]