Right, I listened to all your wisdom, went and looked, tested. Put a B. in my online basket, entered card details but couldn't quite make the click.
Asked Ms AU's advice. She asked the two critical questions; do you want a B? Do you need a B?
Then she asked the killer - what bike would you really like? That was easy, and it isn't a folding bike.
So sincere thanks for your help. I'll be flying to meet my son in October and then starting a new light touring bicycle project that enthuses me! Probably buy a £150 used folder too.