Rising Damp in 1930's house, told that plaster goes down too far..?

yes you have damp ...but if its dry below then its not rising ..more penetrating ..what causes a lot of damp is the way the used to fix the skirting boards ..by all means remove the skirting's and chop off plaster so its an inch above the floor ...but often they would put wooden pads into wall to fix skirting's ..these would be in cross joints ..they all so used cut nails ..square nails ..these gave a great grip but rusted easy and then became a moisture carrier ...and if its a terraced house it could easily be damp from next door ..if on outside walls check pointing