Peter,
as someone with a 'garage full' of 1973 and 1974 bikes (in fact, 75% of my bikes come from these 2 years), i can definitely say that the gold band '531 throughout' decal was introduced (at least on raleighs) in the 1974 model year. In fact, I manufactured some of these decals for some restorations of some internationals:
http://www.ece.ubc.ca/
Raleigh used a rather unusual 'square' reynolds tube co. decal, with a much larger gold area (about 40% of vertical space on the decal). Later (and non-Raleigh) iterations had a 33% - 33% - 33% distribution of 'guaranteed built with' - 'butted tubes forks, and stays', and 'reynolds tube co. birmingham england'.
- Don Gillies
San Diego, CA, 92122