This is the best I can find, a 1952 copy BS loadshttp://files.engineering.com/getfile.aspx?folder=3eeb6c71-6799-46e5-8c88-70eae8945b8e&file=BS-1952_loads.pdf
Go to this website for the definitions:
http://www.deeconcrete.com/concreteglossaryc.html#cement_mixture
based on my fathers old british Reinforced concrete Designer's handbook, 1:1:2 concrete is typically high strength for it's time and is between 4000 to 4500psi.
1:2:4 concrete is standard...