SuperSpecials are known in the records from 1944 to 1951. They were based on a Chater Lea lug design. This design was replaced by the Nulli Secundus -- second to none -- which was presented to the public at the Lightweight Show in 1949 and officially introduced in 1950 as part of the "Latin Series" based on Hetchin's own designs. In 1955 the Nulli Phase II appeared.
The SuperSpecial and Nulli Secundus designs are so similar that they are not infallibly distinguishable by visual inspection. Bell-shaped head lugs usually indicate a SuperSpecial; a pre-war style fork crown invariably indicates a SuperSpecial, but a double plate crown does not invariably indicate a Nulli, as SuperSpecials after 1946 often had the double plate crown. In 1950 the first Nulli Secundus appears in the sales ledger. It featured the double plate fork crown and straight head lugs. During the period 1950 to 1951, both models were built in parallel.
The 1945 catalogue states that the SuperSpecial was built of Reynolds tubing and Chater-Lea lugs cut out to the SuperSpecial pattern (as illustrated on page three). The head tube angle was 74 1/2 and the fork rake was 2 1/2". We have never seen an oval or 'D' fork blade on a SuperSpecial. Nullis may have round or oval fork blades, double plate or other fork crowns.
The Nulli Secundus was advertised as being "a new model which also has a new appearance in lug work" (Cycling, Oct. 1949), though it is obviously nearly identical to the SuperSpecial. There were 79 new Latin Series frames sold from the series' introduction until 8th April 1950, 5-1/2 months after the 1949 Lightweight Show, and over 100 Nulli Secundus frames were sold in its first year of production. There were over 60 SuperSpecials built and sold after the introduction of the Nulli Secundus. In the late 1949 catalogue, the SuperSpecial was listed at £18.9.6, the Nulli Secundus £19.9.6d. The illustrations in the 1949 catalog show both the Nulli and SuperSpecial with belled lugs [for internal bearing races; straight lugs came later, for external bearing races. Now, in the 21st c., internals are back in style again!].
Both the Nulli and SuperSpecial models were produced with and without 'windows' [see fotos below]. This does not appear to be a defining characteristic differentiating Nullis from SuperSpecials.
We can only speculate why the two models were produced in parallel. A number of possible explanations have been offered. The most plausible would seem to be:
a) Hyman knew a good thing when he saw it. The SuperSpecial design had been a good seller prior to the introduction of the Latin Series and he determined to carry it over into the Latin Series with a new name. (Bates already had a design called the SuperSpecial). Other pre-Latin Series models, such as the Toni Merkens and the TRIO, had not been good sellers and were dropped from the programme.
b) Remaining stocks of Chater lugs were built up and sold as SuperSpecials, and any remaining SuperSpecial orders were filled, even after the introduction of the Latin Series. New orders were apparently filled with castings from another supplier (possibly Vaughan) and called Nullis.
c) The defining characteristic may have been the changeover from internal to external bearing races. The 1949 catalog stated the lugs to be Chater Lea castings, not only for the Nulli but also for the MO, Experto and others, and the illustrations for the SuperSpecial and Nulli Secundus showed belled lugs for both. One very early MO is known with bell-shaped lugs and internal bearing races, possibly made with Chater castings; click here. The frame does, however, show other anomalies, including a more modern dropout (with mech hanger), so it is difficult to know how much weight to place on this particular frame (one rider will certainly hold; the whole weight of the Latin Series, maybe not!). Later catalogs no longer mention the castings as Chater and the bell shape disappeared in the early 1950s; straight-sided Latin Series lugs (for external bearings) were apparently produced by another supplier than Chater Lea. It is possible that the SuperSpecial was based on Chater lugs for internal bearings and that very early Nulli and other Latin Series lug sets were also produced with belled Chater lugs, but that all models were subsequently produced using straight-sided castings from some other supplier, such as Vaughan, for external bearings. Further research is necessary.
d) The name SuperSpecial may have designated a complete bike, or a specific geometry (as noted in the 1945 catalog), whereas the Nulli Secundus name may have referred to the lug pattern only.
Ultimately, the final arbiter whether a particular frame is the one or the other is the sales ledger. The sales ledger, however, does not give us any reason, such as a design factor, why a particular frame was sold as the one or the other; it merely confirms that it was. In sum: A frame from 1952 is a Nulli; a frame up to the end of 1949 is a SuperSpecial; the uncertainty pertains only to the years 1950-1951.
The first Nulli, the prototype and exhibition frame, survives; click here. The Nulli Secundus dropped in popularity after about 1960.