To achieve the design (and conversion) a pivot lug was added to the underside of the receiver for the trigger, the rear of the fore end had then to be split where this was and so the rear band was eliminated and a new fore-end cross screw created and installed to pinch the fore-end together slightly and anchor it to the trigger lug on the receiver (through a cross hole). So the Mk2 was essentially a trigger performance improvement - it did make the Mk2 a marginally better shooter, although the official sniper rifles all remained in Mk1 configuration. The Mk1 rifle had the trigger mounted on the trigger guard and its location was subject to the thickness and fit of the wooden fore-end and so the relationship of the trigger to the seer had extra variables.
The Mk2 is hard to differ from the original Mk1 - the key change was to hang the trigger pivot on the receiver so the trigger stayed with it and maintained its relationship with the seer.
A standard (complete) 1949 Fazakerley No4mk2 rifle.