I just checked back through the documentation again after reading your last post and it does appear to allow for tax free growth:
"By legally assigning a Child Savings Plan to your child, your contributions count
as gifts to that child. Provided you stay within the Small Gifts Exemption limit,
the child will not incur any Gift Tax or have their threshold reduced, either when
you make the contributions or when the plan is encashed."
Link:
That means they won’t pay gift tax but i would have thought something like exit tax or capital gains tax would be charged (i hope someone more knowledgeable can confirm)