Your criteria are those for a secondary school teacher, possibly an A Level teacher. I note that you did not list 'love of subject' or 'likes kids' or 'enjoys working with kids' or 'empathy'. The skills, instincts and personality needed to teach/coach a kid aged 9 or 10 are quite different from what your list demands.
I would not focus on my demands as a parent, rather the needs of my child. .... I wholeheartedly echo the sentiments of the previous posters.
Incidentally, I have worked in schools and still work with schools. I know lots of teachers with good Bachelors degrees and quite a few with Masters degrees and PhDs. I have found no correlation between paper qualifications and teaching competence. Also, 11 plus coaching is very, very different from classroom teaching in a school. Some of us have done both.
Good luck to you and your son. But please be careful what you wish for.
Thanks for your input.
Re: Criteria - possibly high, but I have been shocked by the language/numeracy skills of some graduate tutors out there. No harm in attracting the best for your money.
Re: Personal skills of tutor - of course these are important, but can be established (interview & trial) after a tutor meets your primary specs
Re: Needs of the child - indeed, a child needs both in a tutor, a good education and other teaching-related skills
Re: High academic qualifications - point taken, a tutor's quals do not guarantee teaching ability, but they help in getting half way to a good choice of tutor
Do PM me if a good one comes to mind.