The problem wasn't that the silicon didn't stick at all, it stuck very well to the paint on the door, but didn't stick to the finishers. I suspect the problem was I didn't remove the polish from the manufacturing properly.
Anyhow that left me with some horrible silcone on the doors which would not come off. If tried a few things, but today found an old plastic ruler worked a treat. It was one of the brittle ones that kept snapping (watch your eyes) but this gave a nice new edge.
Now it's still not a five minute job, but managed to clean up two of the four doors this afternoon.
It's also worth pointing out there is an obvious change in colour of the paint where the silicon had been compared to the bits where it wasn't. I've used a bit of TCut and it is still there (Sorry TCut).
When I've done all four, will be using some adhesive tape.