I have no idea why the seeming conflilct. It is a Rifle No. 4 Mk I, made in 1943 at BSA, Birmingham (M47). Surplused out in the 1950's, it was proved at that time as required by British law before it could be sold on the civilian market. It was probably bought, along with hundreds of tons of others, by Interarmco or some other U.S. company, and sold in the U.S. for $14.95 plus S&H, by mail order. (A Rifle No.1, MK III went for $9.95.)
The "18.5" is part of the British commercial proof, and indicates the working pressure, in British tons, of the .303 cartridge it is chambered for (40,700 psi). The "ENGLAND" is the Country of Origin (COO) mark required of all goods imported into the U.S. at the time. The GCA '68 changed the law for firearms to require the "import mark" we have today. The COO mark was applied in bond in the U.S., and is not an "English export mark" as is often claimed.
At some point, probably at the end of the war and before being stored as a reserve weapon, it underwent FTR (Factory Thorough Repair) at the Royal Ordnance Factory (ROF), Fazakerly, a suburb of Liverpool.
It is nothing special, though in original condition, they bring a couple of hundred. They are good, serviceable rifles and reliable with the original .303 British cartridge.