If I remember correctly, KE stood for Kaiser Ellison - They were a Sheffield (UK) company who made specialist steels.
An old catalogue I have shows:
KE 672 is (was) a Non-Shrinking Oil Hardening Tool steel to BS 4659:1971:BO1
Composition:
0.85-1.00 % Carbon
0.4% max Silicon
1.10-1.35 % Manganese
0.4-0.6% Chromium
0.4-0.6 % Tungsten
0.25% max Vanadium
Used for press tolls, knives, punches, dies gauges, moulds etc.