[squirrel_hunter]

Torque wrench calibration is an interesting point and something that I should investigate more, but it didn't have any impact on this problem. I can't remember if I was even using the torque wrench when the nut first went I know I did have it out ready. I usually do things up by hand first before getting the torque wrench on to help prevent over-tightening if there is a problem. The nut requires 145nm which is a fair force and I am sure I was no where near the pressure on the wrench required to achieve that.

And for reference I use Halfords Pro wrenches.