I’ve previously owned a Mk1 Soul, and that was with a Salsa shaft seatpost. It needed an initial tweak of tightness of the seat q/r after the first ride but that was all. However this time on a newer Soul, the seatpost needed several tightening tweaks, which I thought was probably due to the gloss surface of the post. I did have a 31.6 spike in a Helius which showed no signs of slippage from the get go. I also examined the fractured area to see if I could find a dark spot, to suggest that a crack was present for some time, there isn’t, it just failed catastrophically.
Okay so I wasn’t on Curbar Edge, I haven’t been there before and after checking the map I was on Baslow Edge, just got to the bottom, slowed down looking for the gate to the lane sat down then ‘pink’ (luckily not followed by a brown) The Thomson layback post fits nicely though, had to back off the q/r which may suggest the spike was undersized?