I have an update.
I decided to speak to my health visitor today to see if she could throw any light on my dd sleeping habits. She made a number of really useful points. She felt that from 18 months onwards toddlers are much more active in their sleep and can find the cot restrictive. She thought that if a toddler was suddenly waking at nightime then there could be real benefits in putting them into their own bed to give them more space. She said in her experience, the benefits outweigh the drawbacks in these cases.
We always go into Gracie as we go to bed and tuck her in. The second piece of advice she gave us was to stop doing this. To cover her when we put her to bed and then not to go in at all unless she was distressed. I never really thought that we could be contributing to the problem ourselves by covering her up with a blanket and thus disturbing her.
The third piece of advice was that given Gracie got her teeth early that she could be teething with molars despite the fact that at 22 months this is generally quite early. With that in mind, I've been scooting on the internet and found a really useful site
http://www.teething-babies.co.uk/teething-process/teething-chart.htmlwhich shows which teeth come and when.
As I'm sure you have all already checked to see if your ds/dd is teething, so have I, but sure enough today when I looked again there they are two white spots in her bottom gums. Gracie's sleep has been disturbed for several weeks but worsened much more over the last couple. The health visitor said that teething pain is much worse for them at night as any pain releif is usually waring off just after midnight and hence the regularity of the night wakings.
I'm now praying that my dd wakings are as a result of her teething and that hopefully when they finally come through, things will get back on track. I hope this is useful and that some of you find a tooth coming in your ds/dd mouth.