On walls and ceilings, emulsion, if loose, can be taken off with a broad metal scraper and water (so can distemper, which softens in hot water, not cold, and may have been used at that age). Emulsion is quite hard but thin and flaky. If it doesn't come off easily, leave it on.
Distemper has a distinctive unpleasant smell when you attack it with hot water, as it is made of boiled-up horses hooves.
On woodwork, gloss paint, undercoat and primer, which might contain lead, is oil based and needs a hot gun or blowlamp (not recommended for lead paint because of the fumes) or chemical stripper to get it off.