The RRA Moderne was not an effort to reuse bits from the old (1948) pattern RRA. The lugs are completely different as are the frame angles. And the components were also different. If anything the 1957 version offered less.. it was sold as a "stock" machine with no options whereas the 1948 one had the pick of the litter in choice British components.
The RRA Moderne, maybe for these reasons, was not well received by the UK cognoscenti and proved short-lived. It proved the very last top-end Raleigh lightweight for the UK market until the 1980s and for the US one until 1969.
Peter Kohler
Washington DC USA