bump?

Evidently, more letters are not available on the internet; perhaps someone has some vintage British specimen books...

Given the size of the type, it's unlikely a full alphabet would have been shown in a specimen book, or in a single document such as a poster.
However, if someone were to attempt a revival, it would be possible from even these few letters, combined with a general knowledge of early sans letter forms.
The shapes are extremely gnarly, however, which is a bit offputting; one would have to make a lot of "warts and all?" judgement calls. The ultra-tight fit is quite interesting, though, and the funny torque of the "N"s.

The lowercase s doesn't quite work, weight-wise, either...

hmm, I'm interested in attempting a revival, what sort of things do you recommend researching as reference?

Personally I find the "gnarly"-ness very appealing..

How big is a "line" in a speciment book, i.e 2-line grotesque, 7-line grotesque?

“#-line” designations started out with a reference to exactly what size was being multiplied — e.g., Four Lines English, Two Lines Great Primer, etc.

Later, I believe that conventions converged on Pica as the foremost basic measure; and 2-line, 7-line, etc., thus refer to multiples of Pica.

so "1-line" was never a fixed unit of size?

Paul Barnes did Thorowgood Sans Condensed.

Look how nice the spacing is in that old specimen. The delicate interplay between counter and inter-letter spaces makes one want to disable tracking for some fonts.

Cheers!