In reply to UKC Articles:
Looking at the photo of Pete actually climbing it would seem the final system he's using is:
1) Rope tied into bi-directional anchor then through the placed gear
2) Rope solo device attached to harness via 2 x locker (can't see if it's tie in loops or belay loop)
3) Light loop of rope then into a traxion, also connected to the tie in / belay loop via a locker
4) Blocker knots as the backup below the traxion (to be untied as they come close to it)
As the traxion will be oriented the wrong way around it can't act as a backup on its own (it's there to manage the light loop) but a blocker knot would jam against it and not go through, so as long as it's connected to the tie in / belay loop on the harness that should be safe (provided you've connected everything properly and triple checked it).
Does look like a huge amount of faff but there is a certain appeal in rocking up to a cliff on your own and getting to the top safely under your own steam without the full risk of soloing it...