There are fewer finer rifles that are a pleasure to own, enjoy and shoot than the peacetime made Lee Enfield No4 Mk2. They have a high standard of fit and finish, feel solid and robust and are a joy at the rifle range, where, due to a magic thing near exclusive to Enfields called Positive Compensation, 1000 yard accuracy can be a normal expectation.
Externally there is one single albeit small feature that tells you if it is a Mk1 or Mk2. Normally on all other earlier Enfields the trigger is pivoted in the metal of the trigger guard, however on the Mark 2 it is mounted to steel blocks welded to the receiver wrist. Externally the difference is tiny.
On the mark one a rivet and steel strap are visible in a small recess at the rear of the forearm, on the mark two this a slotted screw, not a rivet. This must be removed before the forend can be removed from the rifle. The firmly mounted trigger adds to the accuracy of the rifle.