Ok, As requested by Ben, here is a photo I've quickly knocked together to show the location of the 4 factory marked matching serial numbers. The numbers on a unissued 'as new' gun will be in the white as they were applied after completion. The master number is on the body and should never be remarked unless its been converted to L4A2 onwards (7.62mm LMG). Many Brens have had the other 3 location serial numbers removed and the new force matched number applied. These tend to be electro pencilled instead of Pantographed or stamped. Its quite difficult with the lower to know If the original number has been scrubbed and the new matching number applied however there should be other examiners or inspectors markings, steel batch number and or others beneath the original number. If they're not present, they have been scrubbed with the original number.