On the enforcement of stamp duty - this practice is rampant in Ireland. I have first-hand experience with this. It's who you know really. The 'aul "cast a blind eye/lost in the filing cabinet" happens more often than you'd like to think.
You've said this before and it's rubbish. The risk for the person in revenue doing this is enormous so by association the reward for doing so would need to be enormous. It would be cheaper for the person buying to simply pay the stamp duty.