You did not say if this was painted lining paper, if not, then just try wetting it well with cold water with some washing up liquid in. A garden spray is ideal, go over it several time to get the paper really saturated and leave it for a while so the water starts to break down the old adhesive. I used to wet the whole room, and go over it four or five time before picking up a scraper.
If it is painted or emulsion, then you need to break the surface first. The decorator's shops do sell a tool with spiked wheels that will do this. You can also score it with a stanley knife, or even rub it over with 80g wet and dry first.
If that fails, then get the steam stripper out. In my experience I have not had to use a steam stripper very often, its more to do with the getting the paper wet right though and using a good scraper. Get a good quality scraper, with a very ridged blade.
