This may be relevant to other Triumph Models too.
i had a scare last night, I had ridden about 200 yards and noticed the oil warning light was on steady. Stopped and checked the oil level and had a listen, all seemed well so rode home and had a look at the sensor. I tested the wiring by disconnecting it and that was Ok, I was suspecting the sensor itself so went and had a google.
apparently the rubber boot is of poor design and lets in water that can't get out eventually causing a short. mine was soaking wet inside the boot so I dried it off with kitchen paper but it was late by then so didn't test it until the morning which probably allowed the engine heat to dry it out completely. This morning the light went off as soon as the starter span the motor so all is well. I am going to leave the boot off and just put a bit of split fuel hose or something to cover the metal part and the connector.
If you have this type of sensor it might be worth having a look under the boot to check for water ingress. I wonder if it is another Gill product?