Persistent current joints are critical components of superconducting magnets, and improvements in their properties are key to the production of next generation devices. Despite having been made routinely for more than half a century, the science underpinning the performance of joints between NbTi wires remains poorly understood. At this critical juncture, where new jointing methods are being sought for NbTi, it is essential that we develop a sound understanding of the factors in uen...