Barry, as you suggest, Brooks saddles are very common in The Low Countries. The bikes in factories here (yes, really !) often have them as they are far harder-wearing than the modern stuff.
Just what Tony means by "slack" depends on where he's from. If he's from "oop North" then he might mean "coal" but he probably means loose - with the tension off !
If you haven't come across the different spanner sizes yet, then you'd better start tool collecting (a worthwhile hobby in itself !) If you start using English (or 'murrican) spanners on metric bits you'll soon round everything off (believe me, I know, I trashed all the Weinmann and Campagnolo parts on my old Holdsworth because I :whistle: didn't know metric existed !