Recently I got a call from someone who said they wanted to speka to me about an opportunity of some kind, but needed to confirm my postcode before they would go any further.  They said they already had the information but needed to confirm it.  I said that I would like to know something about the company first before giving any information, and after about three times around this conversation the caller decided not to pursue the subject and hung up.  This brings me to a question - does it really matter that a caller can identify your postcode? And an observation - if you really want to protect yourself from questioners, question them back and see how they like it!

You make such a good point. You had no idea who they were, where they were from or what they wanted from you. It's better to be wary of these things rather than giving out details to random people you don't know.