We're not talking about boarding school here. Small children love interacting and playing with other kids. It doesn't harm them at all.
In fact they're much better adjusted than kids that stay at home all the time being ignored with mummy[/quote]

Both of my kids went to a paid nursery (and bloody expensive it is too!) part time as my wife switched to working part time following the births. I can say without a doubt that it help them both as they became more social, less clingy and helped them develop in the early years, I suspect more so than if they were at home everyday and attending a couple of baby groups.

Those are very valid reasons but that is separate from starting school. Actually having them as longer playgroups with some basics like the alphabet and numbers and simple counting would be better than a more formal structure.

But in a formal structure kids learn that they have to stay sat on a chair for a certain period, that there are organised breaks every so often to go and run around. They shouldn't wait until starting school at 5 to learn that.

That's what parents used to do, wasn't it? Teach children patience and how to moderate their behaviour in preparation for school?
Why the sudden need to take parenting away from parents and give it to the schools to do?

Wrong on so many different levels. Playgroups require that you have a parent there so doesn't teach them independence.
A more formal nursery program works wonders on kids.

As an example:
At a recent school play they provided a crèche for kids under 4 so the parents could watch the play.
Of the 15 kids in the crèche only the 2 kids that went to nursery regularly were happily playing when the kids were picked up.
The rest were crying and required 1-1 attention as soon as mummy left them there.

In fact the 2 kids who were used to nursery were actually the youngest and were wandering around trying to console the other kids as they didn't understand why they were so upset

Not in swedish playgroups. The parents go off to work. Few parents about even though each parent is legally allowed 4 days a year in school per child. They do sit down at chairs and sing nursery rhymes and count. They paint at their tables and have a class structure. They do all the things that you want them to learn before going to a junior school.

We don't live in Sweden and what you're describing is what 2 year old kids would be doing at school anyway. They're not exactly going to be doing doing quadratic eqations

Yes but they are not tested and are more structured to being in class and developing at their own rate. Our government will probably start testing them as soon as they can. Doing quadratic equations is something that you do not do until much later.

But testing is important, if anything to ensure that any child with difficulties get appropriate help.

Teachers should be able to identify any child that is struggling.