Restrap City Bar Bag - Black - 1.2 Litre

Good: fits on the Brompton M bars, the waterproofing. Not leather like the prettier handlebar bags available elsewhere. It doesn't interfere with the bike folding.

When the bag is closed to the waterproof position it doesn't seem anywhere near 1L. of storage There's enough for a modern big phone and a small-medium set of keys, and hardly anything else.

There are no compartments, so the keys will scratch your phone every time unless you use a small key bag for them.

I find the clip and bungee surprisingly hard to operate - no way is this possible with 1 hand while riding. I need to stop and use 2 hands. So it's not as easy to use or as practical as a zipped handlebar bag for a road bike.

Still, it does do what you think it's going to do. If you can read my criticisms and think you can live with them, and you want a small Brompton bag to put your phone or your keys (or both if you can arrange for the keys not to scratch the phone) then it's fine.