A lighting 3 pin transformer has failed and Googling "TN20UK" got me a Google thwap (or whatever its called) - one result - but not it.
Its marked 240V 50 Hz
12v 1.67A-20VAmaker looks like TECNE TN20UK
Google shows me lots of things that are not it, I'm guessing somebody here (he hopes) can point me to it?