It didn't work for DS1 until he was about 3.
It works for DS2 though. Over Xmas I got to sleep in until 8.30am a few times...it was light and everything! It doesn't work on the odd day for us, but they CAN adjust over a few days. They all do, otherwise they'd never adjust to the clocks changing.
What is this lie-in of which you all speak? Is that when you sleep until your body has had enough rest and you gently wake from your peaceful slumber ready to greet the day with a smile on your face and a spring in your step?
I wonder how many of our little ones are greeted with groans in the morning?!