Hi all,
My Practical Wireless article was July 2018. Sorry for the delay in replying, I was distracted, it is our 14th wedding anniversary.
I confirm that my clock keeps good time, close enough not to need resetting between power cuts etc., (roughly yearly) There is no backup battery. I don't use the alarm setting, but in another, more complex kit, the alarm time creeps backwards by 1 minute per day..