The complete list of numbered items on the No. 1 are body, bolt, barrel, rear sight leaf, nosecap, and forend. If all there from the factory the font should be identical on the metal parts (the wood I'm not sure about). As others have indicated, No. 4 rifles have fewer numbered parts but I would include the barrel as a key one for value. For example, if you're looking at a '41 BSA or Maltby, the value as an early rifle is obviously raised by having the original barrel. However, certain manufacturers/years didn't number the barrels. As far as the forend on a No. 4 goes, many were numbered at some point in their life. If done as part of an "FTR" program that will usually be apparent from all of the other replaced parts. The lack of a number on the wood on a No. 4, unfortunately, can't be looked at as proof of originality. The final thing about numbers is that they can be factory, FTR, armourer, or bubba.
milsurpo