I have mini pochette in azur and i love it very very much,and yes,it fits my ludlow wallet and car keys!!!!!Pochette was released in 1989 in Epi before the iconic canvas.
Definitely the size will have to be considered for the amount of items you would like to carry in it.
The larger pochette can be used as a small purse or evening bag. The mini pochette with the chain is really adorable and only practical as a make-up bag or a small bag for when you're in a hurry. Would be good only for a few cc's and keys. Too small to accomodate a small wallet including the Ludlow.