There was no protocol that decided which camouflage pattern, ‘A’ or ‘B’, was to be applied to odd and even serial numbers. It is just a made up rule based on what is seen on Spitfires. Just like i before e except after c, it soon breaks down out in the real world. For Hurricanes the ‘A’ pattern is usually found on aircraft with odd serial numbers and the ‘B’ pattern on aircraft with even serial numbers. There are of course always exceptions.
Different interpretations of instructions, revision and alteration of national markings, shortages of materials resulted in more variation in the camouflage and markings of RAF aircraft in 1940 than any other period. Manufactures continued to use the bright red and blue pre-war identification colours instead of the dull colours that replaced them with the introduction of camouflage. When new markings were applied both the bright and dull colours might be found on the same aircraft. When Sky was introduced throughout the RAF, circa June 1940, very little was available and mostly as a gloss finish that the Air Ministry did not want used. The tiny amount of Type S that had been produced was in the hands of the PRU. As a result, other similar colours and not so similar colours were used as substitutes. Archaeology (wreckage) has revealed that two in particular were used, BS 381 (1930) No 1 Sky Blue and BS 381 (1930) No 16 Eau-de-Nil but Sky Grey has also been found. Some units mixed their own versions complicating things still further. Sky proper does not become common until mid-September. Investigation of more wrecks from June/July is needed to give a better picture of events.
Following a meeting at the Air Ministry on 30th October to address fighter camouflage and markings, on 27th November day fighters were to have port wing painted Night (black) and spinners painted Sky and an 18 inch Sky band was to be painted around the rear fuselage. As units began to request supplies of paint to comply with the instructions, 3 MU Milton (where you got your from) signalled the RAE on 18th December to advise them that they had no Vocabulary of Stores reference number for Sky. The RAE was asked to inform 3 MU which shade of Sky, Blue or Grey was required. (i.e., was Sky Sky Blue or Sky Grey?). They then stated they were issuing Sky Blue. (NB The Sky Blue on the Air Ministry list is very different from the BS 381 Sky Blue). As a result contemporary photographs of aircraft often show a marked contrast between the under surface and the spinners and fuselage band painted with Sky Blue.
R4175 RF*R. This aircraft is depicted correctly with the ‘A’ pattern camouflage. NB. 303 Squadron placed the squadron codes, ‘RF’, behind the roundel on the starboard side of the fuselage and in front on the port side. Rotol propeller with blunt spinner. It was photographed being examined after being shot up by a Bf 109E from I./JG 52 over Sevenoaks on 6th September. Frantisek’s top scoring aircraft he was killed in it on 8th October.
P3700 RF*E. During September 1940 303 Squadron used three Hurricanes coded RF*E, P3700, P3577 and P3901. P3700 had the squadron badge under the cockpit, P3901 where it ws usually placed at this time, at the base of the aerial. The Hurricane is depicted in the ‘A’ pattern which is correct for P3901 but not P3700 which wore the ‘B’ pattern. So it is only necessary to move the squadron badge to correct it. According to some accounts P3901 bore the legend ‘We do not beg for freedom, we fight for it’ under the cockpit. Rotol propeller and blunt spinner.
V7467 LE*D. Described in some publications as July 1940 and depicted without roundels on the under surfaces of the wings. (Roundels on the wing under surfaces were not introduced until 11th August 1940.) This Hurricane is illustrated correctly in the ‘A’ pattern camouflage. Rotol propeller and blunt spinner.
V6864 DT*A. This scheme is post-BoB and certainly not October 1940 as painting the under surface of the port wing (Night) was not introduced until the end of November. Photographs of this Hurricane are found in the 257 Squadron winter wonderland set, North Weald, January 1941. Well past the BoB sell by date. This is a very well known aircraft and one wonders how anyone that knows what he is doing can attribute October 1940 to it. We have some very funny weather in this country but snow in October? Not really.
The ‘B’ pattern camouflage is correct for this Hurricane. Under surfaces BS 381 (1930) No 1 Sky Blue (FS 595B 14325). Fuselage band Sky Blue (FS 595B 35550). Spinner also Sky Blue with red tip. Spinner base plate left in Night (black). Rotol propeller with blunt spinner. The serial number was repeated under the tailplanes in 2 inch characters in Night (black). This also very well known as they can be seen in the photographs.
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There is no Sky on me!
BS 381 (1930) No 1 Sky Blue and Sky Blue are available from WEM in their Color Coats range (as is BS 381 (1930) No 23 Eau de Nil).
https://aeroscale.kitmaker.net/news/2898