Trying to find the leak is like trying to find a needle in a haystack!
Stripped the outer jacket off, it’s a well insulated kettle, and a good design.
Found the leak was caused by a build-up of Limescale around the heater plate silicone seal:
Fixing a leaky kettle
scottbouch 
did you fix it?
Yep, there was a limescale build up around a rubber sealing ring wherethe element base is sealed to the body of the kettle. will update photos when I get to a computer…