1974 Raleigh Superbe project: new seat, converting Filson field bag to pannier., a photo by ConserVentures on Flickr.
I looked for weeks for the right panniers. My initial favorite was the Brooks Brick Lane roll-up pannier set, until I found out it was made in China. I just can't justify the dear price for an off-shore make; I have no problem with the made-in-England Brooks products being expensive (such as the saddle).
I wanted the right look for the age and condition of the bike—nothing too shiny, no plastic buckles, no reflector tape, but also not too home-made looking. Duluth Pack in Minnesota makes a nice set, but they were just a little too plain (I know, picky).
Then I hit on an idea: I had my old, well-loved Filson Field Bag (large), which attaches easily to the Raleigh rack via the brass D-rings and leather straps. A simple modification to add an attachment at the bottom, and I'll be set with an easy, appropriate bag-pannier for about-town.