Tomsk,
As far as I know, RML is Maltby. I am sure that if I am wrong someone else on here will say so!
Joe,
Have taken a photo of my two Mk.1 Drill, plus one of the Mk.2.
However, currently having trouble downloading images from camera to computer, so may be a while until I get it sorted. Have noticed, however, that the fluted Mk.1 has a bronze head, whilst the dimpled one has a steel "screw-in" head. Both have very similar headstamps, although the bronze head has a small "broad arrow".
The Mk.2 also seems to be bronze, but is nickel or chrome plated, has no flutes or dimples, and has a steel head with the headstamp 20MM 50 JES, and is stamped DRILL 2 on the case side, just above the extractor groove.
Regards,
Roger.