Welcome to the forum, Luke. Sometime in the '20s the nomenclature of the rifles changed...can be confusing at first.
A quick primer:
SMLE and ShtLE (Short Magazine Lee Enfield) became No.1. BTW the earlier title signifies the two models the No.1 replaced. A longer rifle and a shorter carbine. Not referring to a short magazine, but a short(er) rifle.
P14 (Pattern of 1914) became No.3
Earlier rifle designs not in active service were not renamed. Later rifle designs typically just have the later Number title, well, that is until the 'L' series started and AFIK only the No.4 (T) rifle, a sniper, became a 'L' series upon conversion to 7.62 NATO. There was a stillborn L8 project involving No.4 conversions.
Brad