After a lot of digging and research regarding the TPS, I’ve made a few discoveries.
The throttle position sensor on this bike is a combined TPS, manifold pressure sensor and intake air temperature sensor. It’s a Mikuni component called the Modularised Air Quantity Sensor (MAQS).
Doing some more digging and it appears that it’s used on a number of bikes such as the Suzuki Bandit 1250, the Yamaha YW125 Zuma and the Yamaha YZF125R. I found a YZF125R sensor on eBay for £35 so thought it was worth a punt. It arrived this morning and, indeed, appears identical to the one on the Husky. I’ll need to plug it in to test it to be sure, but I suspect a sensor is a sensor in this regard.
Also, in checking the parts fiche for the Yamaha YZF125R it appears that the throttlebody and MAQS is also a single part there too. This leads me to believe the whole lot is supplied by Mikuni as a single item, with no expectation of the dealer to replace the MAQS.