After much investigation I have narrowed the culprit down to the sunroof drain tubes, where they exit the body of the car in the front door jam. Water is running down the A piller in the door jam, onto the pretruding drain tube and then down into the car, on both sides. Also a sideways rain or when washing the car provides enough water to enter in the panel gap.
My question is - Is there meant to be a grommet or boot here? Or is the best bet to remove the door and seal the around the drain tube myself?
And before anyone says anything, door membranes have been replaced, whole scuttle tray sealed inc around every grommet and cable, all grommets in bulkhead are healthy and drain tubes free and un-chaffed.