I was talking to James Geddes (Traction Repairs) this morning and as far as he could remember (there wasn’t a Slough car to look at) there isn’t an actual ‘seal’ on the sunroof, it’s more of a trim piece ‘nailed’ on the side.
The sunroof when it leaks is normally down to blocked or more likely failed drain tubes.
It will be interesting to see confirmation/pictures though.
David Faulkner