In the mid 1950's Ron Kitching imported Cinelli, the super corsa being 531 with sloping crown, and the model b in some plain guage material, typical of Italian bikes of the time, heavy but nicely built. The SC was in Ivory, quickly changed to orange, and 531. The B was in a translucent green. On my screen yours appears to be blue, so may be later or not bought through Ron.
The Sun is a typical 1960's ish Raleigh mass produced as Carlton, Bsa, etc. in Worksop.
Urago were brought in mid 50's by A P C Bowles, and others. Quite decent but fairly ordinary frame, but looks a bit later. I seem to remember these were made in the south of France, certainly looks French. Gnutti splined cotterless and simplex chainrings, I remember in 1955 taking 50 of these chainsets from Mr Bowles, with the rather poor original 47 x 50 chainrings, and selling them for £2.50 each. They tended to loosen on the splines. Perhaps they had been supplied with the frames.
Most of Harris production was low end bikes aimed at the schoolboy market, as were Carlton. This one is rather better, looks like it had a 49D chainset, some info out there. It was a bad time to be in bike manufacturing. You might find most of his book on line somewhere, were Falcon involved at the end?