Shoulder straps is also on my list
. Need to get hold of some D- rings first. I think also adding a piece of webbing innside the basket when stitching the webbing that holds the D-ringd in place is going to make it stronger, since basket material and design is not really made for a shoulderstrap.
Edit: When I posted this in the Yahoo Brompton forum I suggested that If you want to fill it up often then maybe go for a sturdyer material (in that case you must use a roll top, not a draw string). Also you can add a strap of webbing
vertically around the "stomack" of the basket to keep it together/more compact.
And: fietsbob my dear. Some of us are trying to collect different options for B luggage in one thread to make it easyer for peopel to search and find suggestions for same. I am sure they can judge the different options without your eager advice an always helpful comments. Maybe it is time to do the dishes?