thanks for your replies girls.

Fee, Lachlan has been doing this since he was born. He has not yet slept through one night. six hours is the most he has ever slept in one go.
I have started to decrease the amount i am giving him. I know that he isnt hungry so that makes me feel better about doing it.

I will let you all know how i go!

Oh - Lucy, i have tried the water and he just wont have it. When he has the milk he will drink the whole lot and fall asleep straight away!