Sorry girls - posting problems again. If you want to PM me that's fine, I can answer those even when the board chucks me off.
I was talking about the solves all your problems book which is upstairs at the moment so I will get it when DS wakes up from his sleep. But I'm pretty sure there is a schedule in there that moves away from 4 hour towards 3 meals a day with milk at either end. I think its a harder transition than from 3 hour to 4 hour personally. And like I said, we had to do it from scratch once I worked out what the problem actually was!
I think if I were doing it over, I would write down the before schedule and then the after schedule and see where I could gradually change things. So I think I would try moving naps later at the same time as dropping the catnap. I think I would have given a milk drink with tea so that I didn't have to start that when the evening bottle went. This is all with the wise knowledge of hindsight of course! Who knows whether it would have worked!
I'll post back later when I've got the book in front of me.