No.2 PRU Royal Blue
The RAF Form 540, Operations Record Book for No.2 PRU based at Helipolis in Egyptopens with an entry dated 1 June 1941. The entry describes the origins of the Unit, its operational policy, its organisation and is equipment. Paragraph 5 is headed 'Camouflage' and states
'5. CAMOUFLAGE. The aircraft are painted with “Royal Blue” Dope and with a matt finish. This has proved to be invisible to the eye at 14,000'.'
Just over a month later, the entry for 3 July 1941 again made reference to the camouflage finish of No. 2 PRU's aircraft thus
'EQUIPMENT. Hurricane W.9116 was taken to ALMAZA to be re-painted with a Matt-Blue finish. No. 102 M.U. had painted it with glossy paint.'
On 25 July the ORB makes reference to the formula of the Matt Blue colour as follows
'EQUIPMENT. Hurricane V.7423 returned from ALMAZA where it had been re-camouflaged with blue matt dope. The dope is mixed as follows;- 5 galls, De Lux Bosun Blue, 16 lbs. Zinc Powder well filtered, 7 pints of turpentine, 31 lbs. Black De Lux.'
As can be seen from this, the matt blue finish used by No.2 PRU Blue was specially mixed for the purpose using a colour called 'De Lux Bosun Blue' as its basis. There has been some speculation as to whether the reference to 'De Lux' was a misinterpretation, misunderstanding or misspelling of the word 'Dulux', which was a trade name used by DuPont for their enamel paints by the Officer who compiled the ORB. This might not be so far fetched as it sounds as British Australian Lead Manufacturers PTY Ltd were associated with DuPont and marketed Dulux finishes whilst a link with Middle East Command is provided by part of a letter from the Royal Australian Air Force's Chief of the Air Staff to his RAF counterpart dated 16 July 1941. This stated
'As you may know, two Officers from the Middle East were here in April to place orders for a large variety of general equipment wherever there was a likelyhood of early supply.'
There followed a list of the types of materials ordered which included 'Paints and Dopes.' Thus it is possible that a Dulux colour called 'Bosun Blue' may have been obtained from Australia for some other purpose only to be pressed into use as an ingredient in the mixed No. 2 PRU matt blue.
There is no known sample of this colour, so it is impossible to say with any degree of certainty what it might have looked like. The photographic record does however appear to indicate that it was a dark blue, slightly lighter than that used in the British national markings which had a theoretical specular reflectivity of 4%. The late Geoff Thomas, who as far as this author is aware was the first researcher to come across this colour, stated that it was an ICI finish and likened it to BS 381C No. 105 Oxford Blue and FS 25051, and as having a specular reflectivity of 6 %, though on what evidence this was based is unknown.
Since this colour was first made known to modellers, there has been a tendency to simply refer to it as 'Bosun Blue' which is incorrect as this was only one of the ingredients. It is therefore proposed that a more accurate name for this colour might be 'No.2 PRU Royal Blue', which takes into account its origin, purpose and hue.
There is some question as to whether No.2 PRU Royal Blue was the only shade of blue being used in the Middle East by the summer of 1941. One of the most intriguing aircraft to serve with No.2 PRU during this period was a Beaufighter Mk. IC, T3301 which was allocated to the Unit on or about 12 August. An ORB entry for Heliopolis dated 18 August 1941 stated that
'Beaufighter T.3301 was flown to No. 102 M.U. to have camera's fitted and the cannon guns removed. Three 20'' camera's are used.'
This was followed by a further entry dated 1 September which stated
'The Beaufighter T 3301 is at EDKU, also being fitted with 20'' cameras.'
The entry for 21 September recorded that 'F/O Pearce Collected Beaufighter T 3301 from IDKU; BOAC servicing unit started work right away on camouflaging with dark blue.'
The problem with this is that the few photographs to have emerged of Beaufighter T3301 appear to show it to have been finished overall in a colour which is noticeably lighter in hue than the Blue of the roundels. This is much lighter than the tone visible in those photographs which are thought to show the No.2 PRU Royal Blue finish, but there is absolutely no indication of what shade of 'dark blue' this might have been. It is interesting to note that the Beaufighter was painted by what were presumably civilian contractors. Whether this had any bearing on the finish is unknown.
Spitfires and Mosquitos
The decision to equip No.2 PRU with PR Spitfires led to a letter being sent from the PRU at Benson to HQ Coastal Command on 29 January 1942 enquiring as to the colour scheme to be applied to the Spitfires being prepared for dispatch. It was observed that though the PRU could vary its camouflage, current instructions called for application of either the Temperate Land Scheme or Dark Earth and Midstone on the upper surfaces with Azure Blue under surfaces for operational aircraft overseas. Benson wished to know whether the PRU colour scheme, presumably overall PRU Blue by this time, was required, or whether they should conform to the scheme applied to the Mosquitos operating in the Middle East should be used instead.
The reply on 25 February stated that aircraft for the Middle East should proceed there camouflaged as they were at present and that the necessary camouflage would be applied to them when they arrived. Photographic evidence suggests that following their arrival the Spitfires were finished in No. 2 PRU Royal Blue. Ultimately, from 1943, increasing standardisation saw PRU Blue become the predominant colour on PR aircraft in the Middle East.
The reference to a Middle East scheme for the Mosquito appears to have been a reference to the camouflage scheme applied to the two Mosquito PR Is that were sent out to Malta from Benson for trials in early January 1942. These would seem to have been finished in an unusual camouflage scheme which was described in the letter of 29 January referred to above thus 'Top Surface: Medium Sea Grey and Mid Dark Sea in equal parts and equal parts of Grey and Medium Sea Grey. Bottom Surface: PRU Blue.'
Thus it would appear that the upper surfaces were finished in two bespoke colours which were specially mixed with PRU Blue under surfaces.
What these colours might have looked like is an almost complete unknown due to the unusual nomenclature used to describe the colours. Clearly both the upper surface colours were mixed from Medium Sea Grey and another colour, but what exactly was meant by 'Grey' and what was meant by 'Mid Dark Sea'?
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