I've been using vinyl products from aurora boat products
https://auroramarine.com/I clean the vinyl top with meguires vinyl top cleaner.
Then I apply the vinyl preserve from aurora (made for boat seats, etc) (vinyl guard)
Then I go over the seams with the aurora seam sealer made for sails. (Dri-stitch)
The seam sealer eliminated about 85% of the overhead drips! I apply it at the beginning of spring and it lasts all year.
Looks like Moore Marine in manchester is the UK distributor.
No vested interest. Just kept the rain out!
