I tried to find this coin too by searching over 390 pages of likely candidates, but then stopped to do other work.
Now I return to Roberts this morning to pick up and find it just on the next page. All too late anyway since others already nailed it. I found "Monogram" of Hainault on page 392/393. It's in a section called Northern Types- Monograms or Symbols: Silver Coins of Medieval France. Could be Roberts 7505 or other very similar. Sorry for the delay but there's rib cooking and wallpaper stripping mixed in with coin hunting.