I have been constantly on this topic for the past 2 years mostly lurking sometimes posting. My ds who is now 2.1 has been a rubbish sleeper and an early riser (5-5.30am) for a long time. I tried many different things to solve ait and nothing made any difference.
We went away to Centerparcs a few weeks ago and he had a few later than usual nights. Anyway the upshop was that he slept until 6.30am on the 3rd morning so I decided to use the opportunity and from then on for a couple of weeks put him to bed at 8pm instead of 7.30pm. It worked!!!
I have gradually brought his bedtime back to 7.30 and he still sleeps until 6/6.30 which in our house is a serious lie in!!
Anyway I don't know if we broke a cycle or if he was just ready for it, but I just want to share it with you all and say not to give up hope!
Good luck to all of you!