Found this info via RSOC on the RS's:

1981 - RS1600i previewed Sept, LHD versions on sale shortly after
1982 - The Ford RS1600I goes on general sale, in UK Oct in RHD
1984 - The Series 1 RS Turbo is Previewed Oct , Goes on general sale at the end of year.

Does anyone know the exact dates and also when the lower-spec models went on sale?