Hide + Seeker Wald basket bag
These bags, made in Newcastle, are constructed from X-Pac and Cordura fabric. The fabric is waterproof (though not seam-sealed). They come with a shoulder strap that doubles as the attachment to the basket.
Lot's of room to store with a long roll-top closure with velcro on the inside, plus a strap with buckle to cinch it closed.
They're perfect for Wald 137 baskets (the smaller size).