Hi have a Super Lenton which is currently having a spruce-up, it'll not be going back to original but will still be recognisable.
I belive it's from 1954, (T serial number) it's the model previous to yours, blue with chrome socks, earlier lug pattern and no bare brake cable braze ons under the top tube. The 4 speed FM hub is dated 1954 as is the front Dyno-hub.
It was painted with a heavy coat of Dulux time-trial black when I got it and I've been stripping it back but to the original finish but he paint has not survived very well. Interestingly when I revealed the original 531 sticker on the seat tube it appears to indicate that the frame is built with butted tubing - which was supposedly not introduced until late 1955 for the 1956 season.
This looks like another of the inconsistencies between Raleighs frame numbers, catalogues and the actual production date changes, I've come across many whilst restoring my 1940s/50s RRAs (2 of which have frame numbers that are non-existent in any published Raleigh records.