Chris Holmes was thinking very hard :
Thing is, in my limited experience, transistors and chips required a power
supply of some sort to convert mains to 5V and or 12V DC. But I couldn't see
anything on the board that I recognised as being capable of doing this.
Are there now 240V AC chips? Have there always been and I've just not come
across them before?

It will use a triac for switching and likely a mains rated capacitor
and diode as a capacitive dropper, to reduce the mains voltage down to
a useable AC voltage.