Dee Verma
the water could be coming in from a frame that has not been sealed properly from the outside, or from the base of the frame not sitting fully on the outside sill. driving rain is pushing water in.at the base or the surround - if the frame is not sitting fully of for that matter is not level on the brick work it will have the same effect. if water is on the plaster then there is a bridge being formed between the internal plaster and the outer wall., in which case remove frame and install a DPC membrne between the cavity.to stop the travel of moisture. hope this helps.
