Ceiling is irrelevant...
Must not the DH (200ft in this case)
be below the ceiling (100ft in this case)??
DECISION HEIGHT [ICAO]- A specified height in the precision approach at which a missed approach must be initiated if the required visual reference to continue the approach has not been established.
Note: The required visual reference means that section of the visual aids or of the approach area which should have been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position, in relation to the desired flight path.
Of course maybe they could see through the clouds.