2002 Renault Espace Rain leaking in over windscreen

My 2002 espace has a serious leak over the windscreen when it rains. The water mainly drips down on the rearview mirror, but can appear anywhere inside along the top of the windscreen, leaking across from one door top to the other (although it's much less on the drivers side). There is no sunroof fitted and I have put waterproof tape across the entire length of the top of the windscreen on the outside(and the re-entrants above the front doors) and the area around the centrally mounted roof aerial to stop the leak. I have to place buckets on the centre of the dash and in the passenger footwell because of the amount of water that leaks in when it rains. I cannot understand where the water can be leaking in from HELP!