Its unofficial but everyone knows we love Brompton, and to celebrate our love for this brand we have made 2 of our best loved styles Brompton-compatible. All you need to do is to buy the frame and slip the bag on.
These are the six current Goodordering styles that attach onto the Brompton block
Beware some of the handlebar styles of the brompton might touch the top of the bag, it might get in the way a little big, and ideally the bag should be a bit shorter but it still does work and attach on easily. The main bonus is that you can also use the bag as a backpack as well for times when you are not on your bike :)
The frames are currently a little hard to get hold of, but here are some links.