Just for some better images I've shot everything again and larger. [This link] represents all the frames from one roll. [This link] represents all the frames from a second roll. BTW, I have no way of knowing if these two rolls were in the same tank for development. I also tried to magnify this even more [link here]. The pattern seems very uniform parallel to the length of the film but wavy running across the frame. I think this probably rules out the imprint of a material pattern - one direction of the weave would not be so uniform while the other was not.
Today I have also locked myself in a darkroom and thoroughly checked the pup tent with a bright torch - no holes found - didn't really expect any as its a new tent and there were at least 4 rolls in there at any one time and the damage on the HP5 is only reflected on a couple of rolls.
Again as a note to address some oversights above: this is NOT bulk loaded film. Just normal canisters