[yummyfajitas]

When a minimum wage was introduced in the UK unemployment went down, at least for a while.

This is because politicians are (usually) smart enough to introduce minimum wages only during growth periods and to keep the minimum wage well below market rates.

I won't speak about the UK, but in the US, less than 4.5% of the poor earned minimum wage [1].

http://www.bls.gov/cps/minwage2007.htm

When the minimum wage is raised significantly higher than market rates, the results can be devastating.

http://washingtonexaminer.com/node/127791

[1] I'm dividing 1.7M min wage earners / 37.3M poor people to get an upper bound. The real number is less since many min wage earners are teenagers or spouses from non-poor households.