Despite adjusting the door I was unable to stop the leak. Although only small, water was leaking onto a fabric trim panel. In the end I bought some P42 Section from Seals+ Direct and used Evostik to bond it to the the underside of the door opening. It has been totally successful for an outlay of fifteen pounds or so. Also, the top of the door is now dry when it is opened and doesn't drip as it did previously.
Here are a couple of photos showing a short length of seal that I tried before installing it for the entire length.