The zip up Brompton cover / saddle bag is quick and easy to fit and remove and can be drawn tight around the base of the bike using its drawcord.
It can be partially unzipped so that the saddle is accessible for carrying the bike while the rest is still covered.
The cover comes with a saddle bag for storing the cover in, which attaches to the saddle bag hooks on the back of a Brompton or Brooks saddle.

Brompton Q part code: QCOV
Brompton part number: 9030286