This arrived here, I had another look at the Tap settings and found the
option to enable the Hands Free mode right under the Battery status on
the HTML web page
Just to summarise again for those who don't know.
The Echo Tap is different from the Main Echo and the Echo Dot in that -
by default - the Tap doesn't listen for the wake word "Alex" followed by
a command, the user must press a button and then speak the commands.
With the Hands Free update the monitoring for the wake word "Alexa" can
be enabled thus the Tap functions as does the Dot etc though be warned
that this function will drain the battery significantly.
My suggestion is that you disable Hands Free if you intend to use the
Tap a lot on battery and enable it if you're using the Tap through its
mains adapter or a power bank.
Also note that Tap can be put to sleep with a simple short press of the
power button.
