I am a touch unsure about the date of this Owner's Manual. It has the 'rectangular' Brompton logo on some of the images. This logo was trademarked in 1996, so this manual may very well date from after this. It also seems to predate the 2002 Owner's Manual. I have been told that this manual dates from 1998, which at least seems possible.
It does not include coverage of the Brompton 2-speed derailleur, but does include the Brompton chain tensioner.