In reply to 67hours:
Image Scotland are a sister company of Scottish Mountain Gear and do this sort of thing, based in Musselburgh outside Edinburgh. They offer Gore-Tex personalisation including embroidery, and can certificate it as tested and approved, as Scottish Mountain Gear are authorised Gore-Tex repair people.
I've used them before (for more conventional t-shirt printing) and they've been very good.
https://www.imagescotland.com/personalisation/goretex