Manufacturer of this No 32 Mk I scope?

[Peter Laidler]

That method of marking was called the 'lead loaded method' The etched, very shallow drum markings were over laid with lead/solder then wiped clear. Once the scale was acid blacked, it was heated and the melting solder would appear through the blacking. Pretty ingenious until you needed to re-whiten the scales, then it's crap as the engraving is too shallow to take the quikfil!

This was also used on No2 binoculars too