Patch Repair
Patch repairing plaster can be difficult and if you are not experienced you can often tell where the plaster has been feathered in so its best to get a professional in to do the job.
Often when you remove wallpaper from a wall or decide to decorate you will find that a small amount of plaster will fall away exposing the brick work behind. This is quite normal but before repair can begin it is a good idea to tap the surrounding plaster with your knuckles, if the plaster sounds hollow then this too is loose and needs removing!