With the polygraph "test" not really being used in the UK I hadn't realised how bogus it was (or at least appears to be):

http://antipolygraph.org/faq.shtml

I took one when I was a kid to get a job in as a stereo salesman. The idea that it could detect if I was not telling the truth kept me honest. The person giving the test (interrogator) is the biggest factor. A good one can get the truth out of you without the machine. It just helps them to "make" you tell the truth.

Now that I am older I realize that it was a big invasion of my privacy. I would not do it again.

I got the job.

http://www.skepdic.com/polygrap.html

That Nixon quote is a classic !

I took one 17 years ago (when I was 17 yo) because Loss Prevention was accusing me of stealing car stereos at a store I worked at. The woman doing the investigation was damn sure I was the one and would not lay off until I agreed to take one. I passed, but I was soooo damn nervous. While I don't think they are anywhere near infallible, and should not be allowed as admissable evidence in court, it was correct in my case, thankfully...
The test consisted of questions specific to the stereos as well as ones like "Have you ever stolen anything in your life?"

We learned to beat them in my psych class in college. Was kinda neat. Anyway, a trained professional can usually beat a polygraph anyway. Ever wondered why Middle eastern politicians always wear sunglasses? It's because the eyes usually give away when you're lying. Pupils have a tendency to dilate when you are lying and you have a tendency to glance up and left when lying, up and right when trying to recall information. Again, this is not infallable, and can be beaten, but hey.