thanks for all the suggestions. removed the ceiling rose and noticed that around some of the wires it looked black and as if the wires had melted a little (the last time i checked the trip switch when it went off again sparks came from the light fitting) someone is coming out tomorrow to check it.
on sunday night my son flooded the upstairs bathroom (using the end of the bath as a slide ! :x ) and since then the downstairs lights keep tripping. there is a light on the ceiling directly below the bathroom. will it dry out or will i need to get someone out ?