Entire books have been written on Lee Enfield Rifles. You'll have to narrow it down a little.
A Wikipedia search for SMLE will help you get started.
Can still be found in use around the world
The 'E.Y'. rifle was named after Sir Ernest Youlle who invented it, or more accurately, adapted it from the standard Lee-Enfield rifle
Many books have been written on the Lee-Enfield. Good luck.
1917 lee enfield
See the link below to a good Wikipedia article on the Lee Enfield. There are several DIFFERENT .303 Enfield rifles.
£275 at least
Seerial numbers are not unique to only one rifle. The year of manufacture is frequently stamped on the metal band at the wrist, or the left side of the receiver, depending on which MODEL Lee Enfield you have.
See the link below for a short treatise (with photos) on the various Lee Enfield oilers.
It will be marked on the weapon itself as to who made it.
$50-400 depending on condition and Mark.
The Lee Enfield .303 bolt-action rifle
The SMLE. Short Magazine Lee Enfield rifle. Picture above.