Developed in Canada about 1943, the Lightweight Number Four, or Long Branch Light Rifle, comes in at 42 inches in overall length and weighs only 6 pounds, 10.4 ounces, a notable reduction in combat load for the Commonwealth rifleman. In a technical bulletin published on the subject, it was called out as being of interest both as a general issue item as well as for the "Far Eastern Field" in particular, a niche that would later be targeted by the more famous Number Five Jungle Carbine. While the Lightweight is designed to use a number of off-the-shelf #4 SMLE components, some radical changes were made to the configuration. The most profound alteration is the removal of a significant amount of material from the receiver, in particular a long section of steel from the left side of the receiver, a deeper milled-out channel behind the safety lever, an aluminum alloy trigger guard assembly and the deletion of the buttstock socket. This socket, one of the signature features of the Lee-Enfield virtually from conception, is completely absent from the rifle, and the traditional two-piece stock has been replaced with a one-piece assembly with a shortened front profile to match the shortened barrel, aluminum forearm cap, grasping channels cut into the forearm and handguard, a reinforcing bolt just ahead of the thin straight wrist, a Hawkins brand recoil pad and a set of very deep (approximately 5/8ths of an inch deep per side) lightening channels cut into the buttstock. While the recoil pad is a commercial component, the presence of a recoil pad is explicitly mentioned in the technical bulletin. There are a few military proofs on the components (in particular the Canadian variant of the Broad Arrow), and the bolt and receiver are numbered "J-5550-19", suggesting that this might have been the 19th Lightweight Rifle in the trial run. While well made, the Lightweight did not find any interest with the Commonwealth. A series of trials performed by the British found the rifle handy and a good shooter, but concerns about the ruggedness of the new socket-free wrist and later severe accuracy issues due to issues with the bore lining resulted in only a handful being produced, with an unknown quantity damaged or destroyed during testing.

Very fine, with 85% of the original black finish showing some light wear and handling marks overall as well as some bright edge wear, especially on the alloy components. The stock is very good with some dings on the handguard and mild handling marks overall. Mechanically excellent. One of the great rarities of Canadian military small arms and of the Short Magazine Lee Enfield in a condition that would be difficult to beat. Worthy of a place of honor in an advanced collection.