General Election 2019

Generally, older people earn more and therefore pay more tax.

Yes but they have this annoying habit* of reducing in numbers by dying or retiring, and when they do the later it's flipping' expensive. This is why shrinking populations terrify governments so much; there simply isn't enough new blood to pay for the promises made to the old.

I'm not clear how this thing of the "young" paying for this specific policy is going to work?

As above, they will borrow the money to fund it. As I understand it.

Also, what about all the NI contributions the women in question paid? Yeah, I get that NI isn't really "insurance", but even so...

Well, it was spent. To pay for the pensions of...

* other annoying habits they have: getting better at hiding their income, not earning significantly more money for many years.