It's OK, not particularly padded so you may want to look at padding out with bubble wrap and clothes (it's big enough that you can pack quite a bit around it, I used this plus hand luggage for a two week work trip to NY) but it does the job.
That would be ace! I'm off to Berlin for Rad Race Fixed 42 from 16-19 June and as my other half is coming we're taking my race bike and the Brompton. The bikes are going by van not flying so this bag would be amazing. I'll send you a private message.
I've got a hard case as well, if you prefer. Although to be honest, if it's going in a van, it doesn't need much protection, the brompton will probably be the sturdiest one in there when folded.
I have one of these that you're welcome to borrow https://www.vincita.co.th/collections/folding-bike/products/b132b-soft-transport-bag-for-brompton-bike
It's OK, not particularly padded so you may want to look at padding out with bubble wrap and clothes (it's big enough that you can pack quite a bit around it, I used this plus hand luggage for a two week work trip to NY) but it does the job.