“you need a passport to get out of the UK and back in again, but not to get into countries that subscribe to Schengen.”
“It simply means that whilst we and all other Europeans have free access to the Schengen area,…
“As I said I can't remember when I last needed to show my passport in what is now the Schengen area.”
I think there is some confusion, naomi, either in what you are saying or how it is being interpreted. You need a passport to enter and leave the UK. But you also need a passport to enter a Schengen country from a non-Schengen one. It is only “inter-Schengen” crossings that are free of passport control. I travel to Schengen countries (France, Spain, Greece, Netherlands, Germany) from the UK quite often. I sometimes don’t need to show my passport when entering those countries (usually because the border control staff cannot be bothered) but I know I can be asked for it and I am always ready to do so. Some countries have separate border control arrangements at their airports for arrivals from other Schengen countries.
There is no difference in passport requirements for somebody arriving in a Schengen country from the UK as there would be for somebody arriving from (say) the USA. But once in the area the free access arrangements apply to everybody there, wherever they originate from.