Well I didn't remove it, White Van Man did, coming at about 40+ through Rufford ford when I was going the other way at about 20+ ... and the watersplash pushed the whole top windscreen trim up and out and drenched the whole interior!!
It does hook over the screen, and it also curves around the roofline IIRC and is siliconed/whatever in, and is a bs'tard to replace partially. If I were going to do it again I'd take the whole screen out and do it all properly.
Pic 1 shows 'the bodge' ... white bathroom sealant, needed that morning as we were off to Tong, as witnessed by the mud and strop left on.
Pic 2 shows it re-done with Landrvoer genuine Flexible adhesive sealant, (STC 50551 of which I have 1 tube left, but dunno how good it will be as I've had it a year)
There's still a part of the top trim that 'bulges' but it's sound to screen and body and doesn't leak at all.