Ann our sleeping improvement did come with my stopping night feeds. In my case I decided to stop feeding (day or night - that was where I was at, I am not suggesting that to you), when ds2 woke I offered him a cup of water or milk (he was already a proficient at drinking from a cup - I am not sure if Seb does that, or has a bottle?). He was quite unimpressed but I didn't feed him, and I can't remember exactly but he was certainly sleeping through very quickly - a matter of days - and that was going from a starting point of waking four or five times a night some nights. I couldn't believe it.
I am also a grobag girl and the only time we haven't used one was when we were in France over the summer and it was just too hot.
I swear by his routine as well (and I wasn' a big routiner with ds1, who was a poor sleeper and still hates going to bed). For me it's easier because ds2 easily recognises the signs of going to bed. We've not exactly reinvented the wheel!
Bath
Roam around his room naked
Nappy / PJs
(sometimes a 10-15 min ramble downstairs if he's not tired, or stories in his room)
Grobag
T bear
Sit down with him on lap & read one short story
Transfer to cot, he puts thumb in, kiss, night night etc, side up, light off, door.
DP probably does it slightly differently but main elements are same.
And if ds doesn't go to sleep happily and easily, chatting away to himself we are AMAZED. It does happen but it signifies to us that something is wrong. We always count our blessing that he sucks his thumb, I must say.
Then I go downstairs and start negotiations with ds1 to go to bed and it is the same old battle story it's been for the last eleven year...