My problem is that paint always peels off the ceiling in a particular room only a couple of months after re-painting it. There is no dampness but yet it just flakes off.

This problem is very common on ceilings. It is the same problem more or less as exterior emulsions flaking off outside walls. There is a very simple solution to this.
Scrape and brush off all the peeling areas and take care to remove blisters and bubbles which have not yet burst so that you can get it down to a nice clean and tight surface.
Fill and sand any cracks or potholes with a spot of filler if necessary.
Mix the E-B into your emulsion at a ratio of 1 part E-B to 4 parts emulsion which should be ample or if you want a really strong mix, go as far as 1 part E-B to 3 parts emulsion.
Take particular care not to use E-B in your second coat. If after you’ve applied your first coat of emulsion and E-B mix, it still looks like it needs another coat, apply a coat of emulsion, but this time without E-B. If you have some of the emulsion and E-B mix left over you can use it as a first coat somewhere else. Better still, just mix up enough to do the ceiling in question, and keep the remaining E-B in the shed for another time.
Should you wish to re-paint this time with an oil based paint, the preparation is the same, but instead of using E-B, you mix in a material called Owatrol Oil into your first coat of oil based paint at a ratio of 1 part Owatrol Oil to 3 parts oil paint (undercoat). In this instance, you can add about 10% Owatrol to your finish coat to help it flow out and ease application.
E-B and Owatrol Oil is available in all the better paint outlets.

After that all you need to do is pick up a can of emulsion and one litre of E-B, also known as Emulsa-Bond.