Hi, I guess many of you may already be aware of these, but if not:
I stumbled across some Swann-Morton blades on Amazon that fit the Stanley Pocket knife as used by Paul. A bargain at £5.95 for 50 blades with free delivery, so I ordered some. They do indeed fit the Stanley pocket knife and the blades come neatly boxed, which doubles as a dispenser, and are individually wrapped. The only visible difference is a slight variation in the the shape of the hole where it clips into the handle (see picture), but they fit the knife just fine. Time will tell if they last as long as the Stanley ones, but at the price I thought well worth a try.