bin liner BrE
rubbish bag BrE
garbage bag AmE
trash bag AmE

How about carrying around a bin liner or similar into which the brompton can go?

Most strips featured the bin liner being callously killed at the end.

It was still in its bin liner, to keep it sterile.

When his flat was searched, human remains were found inside black bin liners in a wardrobe.

In the end, to draw matters to an unhappy conclusion they all agreed that it had probably been a bin liner.

A young man was seen taking clothes out of the house covered in a black bin liner.

Then he picked up the bin liner and Cleo walked him to the door.

I bought it from him for not very much and he gave it to me in a black bin liner.

Danny reached into the wardrobe and found a bin liner.

That's great, but what happens when you forget to take the bin liners to the curb for pick-up?