Am I allowed to be cynical. Is this about the shortage of teachers in key subjects such as science, maths and modern languages?
The government is laying greater emphasis on what they consider core skills over subjects like media studies, but realise they don't have enough teachers. (In part because people with those subjects leave university and go into better paid jobs in industry and professions.)
Private schools, with greater flexibility have addressed the issue by allowing career changers to teach without formal qualifications, presumably if those applicants look as if they will be better teachers than applicants with teaching qualifications. (I assume that if they had a ready supply of talented and qualified teachers in shortage subjects they would hire them.) Presumably established private schools, like the ones Nick Clegg and Boris Johnson went to, feel they can provide sufficient support for those new to the classroom, including at least in some schools, day release for training.
As well as academic private schools being well established with support available from experienced colleagues, they have pretty homogenous intakes (not a cue for a MN debate I hope!) and small class sizes. They also have more scope to clamp down on unruly pupils, so not having training in classroom management skills may not be as critical.
Schools tend not to give parents much information, but again observation is that there is significant turnover of "new" teachers. Presumably some find they don't like teaching, and others perhaps are struggling. The ones who stay though are great, and are able to convey an enthusiasm for their subject and real life experience. Guessing but I am pretty sure that a couple of DCs favourite and most inspirational teachers are not qualified.
I considered retraining as a secondary teacher when my children were born. However the entry costs in terms of not just fees (though there were inducements as I was offering a shortage subject) but also childcare, were offputting. The college had a nursery but nursery places were oversubscribed and only allocated long after I would have had to accept a place. I was also not sure, after talking to friends who were teachers, whether I, as new teacher in an inner city school, could manage classroom discipline, and so felt unwilling to invest the cost of a nanny or private nursery for two children in the hope that I had what it took. A pity as I think it would have suited me, and having school holidays would have made a huge difference.
I can see why in a similar position good mathematicians, scientists etc might be attracted to jobs in private schools. Not necessarily a bad thing as it means that the overall number of people available to teach these subjects is increased, and private schools are not drawing so heavily from the limited supply of qualified staff.
However what works in one context wont necessarily work across the board. Throw in a few variable like more challenging classroom behaviour, larger class sizes, fewer sanctions for misbehaviour, wider ability ranges, the absence of an established team of colleagues able to provide support or to step in if things are going wrong, etc and such an approach could be hugely damaging.
Sorry about the essay.