That decal/transfer you have Jerry dates sometime between 1975 (Raleigh registered the '531' trademark then) and 1977 (Reynolds Tube Co. Ltd. became Ti Reynolds Limited (a formal name change only, Ti having been involved from some time previously).
I started this page to try and explain it a while back and I guess it's not quite complete however if anyone wishes to add decals / dates for the 531 butted tubes I'd appreciate it.
Bob Reid
Stonehaven
Scotland