"the entire focus of what you have provided is on Maths."
a) That was the original topic of the thread. sorry for staying on topic.
b) Read them again. Only the SMPY studies are specific to maths. Acceleration works for all subjects.
"How does a DC cover a wide breadth of subjects if they are accelerated onto a maths degree course at University"
a) Dual enrolment. Already discussed on this thread.
b) Have a look at Miraca Gross's book. She describes children who skipped three or more grades, re-invested one of them to study twice the normal number of subjects at A-level equivalent, and still managed to start university at 16.
"No one has suggested leaving a child to stagnate for several years as being a good option"
You have advised others not to do GCSE in primary because even though their children are bored rigid you think this will make them even more bored at secondary. You have also acknowledged that your own child is extremely bored in maths classes. How is that not stagnation?
"Have you actually read those policies"
Yes I have read them. Your posts suggest that early university entrance is not an option. There is a big difference between non-existent and rare.
"You are equating 'grade skipping' with 'taking exams early' with 'receiving curriculum content appropriate to them"
Erm, no - you are. I've lost count of the number of times I've stated the need to distinguish between the curriculum and the exam.
"acceleration by a year (no more) is sometimes successful"
The radically accelerated Nobel laureates I listed further up the thread mustn't have got the memo.