after an enquiry reference what can be done about a freezing cold bedroom, the home was visited and room examined. Fortunately the room wasn't inhabited by a ghost, on checking the roof space it was found that there was only a miserly 25mm of insulation in it.
The solution, straight forward really add 170mm of new insulation to the roof space. Job done. Insulation is now level with the top of the joists giving a highly improved thermal barrier.
Don't forget to insulate the loft hatch.