Thanks all for your excellent advice.
Looks like a clear choice between the IslaBike Cnoc 16, or the Ridgeback MX16. I’m edging towards the Cnoc, but there really doesn’t appear to be much between them.
As for IdleJon’s concerns, no need to worry, although I’ve not yet had the chance to ride alongside my 3 year old, I’ve been encouraging him to keep his balance on 2 wheels with the Like-a-bike MTB. He’s manage to ride down steps and steep banks as well as rooted singletrack, all the time with me either running alongside, in front, or behind him, to catch him at the point he might fall, or holding the bars to assist. Admittedly, he’s has his knocks, but it goes with the territory and I want him to be comfortable with that. Despite the occasional spill, he always get straight back on and tries again.
Looking forward to the day we can ride together…