Ok, so my thought is that users who received the update, which contained the bug causing excessive energy consumption, also gained the Heuer-01 watchface. Since that update was "pulled", not everyone got it and therefore lack the Heuer-01 watchface.
It's great that those users in the UK who have now received the N7G471 update this weekend are now seeing it.
My Connected is still running the NXG12F build and doesn't have the Heuer-01 watchface, even though my phone's TAG Heuer app received an update overnight. This tells me the Heuer-01 watch face is part of the watch-build update.