You wrote that the council of Cambridge University consists of 16 members elected by academics and seven others. That is not how the arithmetic looks from here. We academics elect 12 from among our number.
Then there are four masters of colleges (often not academics), two external members and three students.
If the number of externals were increased to four, then the masters, externals, students and the vice-chancellor would between them have 12 seats - the same as the number we elect from among ourselves. And the vice-chancellor has a casting vote.
So, by my reckoning, a further two external members would end our long tradition of being a self-governing community of scholars.
Member of Council