Just thought I'd share this today as it's a bit of a revelation for me - so for all you NVT lovers out there, this could be the cleaner for you! I'm cleaning down my latest ebay find - Bayswater - stains all over it. I used Angelus Easy cleaner - there are 8 pics attached to look at - the first 4 are before cleaning and the last 4 are after cleaning (although still drying). I've enclosed a pic of the cleaner which I got from Amazon (as basically I own all the other cleaners and none of them really work).
My advice is as follows; do it a panel at a time - work on each side of the bag individually ensuring it is fully dry before moving to the next i.e. front first, let it dry then move to the back. I used a micro-fibre white cloth and used a clean piece on each panel. Don't over wet the leather (it says this on the cleaner) put a small amount of cleaner on the cloth and clean a small section of the panel, using gentle circular movements - do not press hard on the leather. Move on quickly to the next section to clean in that panel. That's it! You will see the results in about 20 mins!