Not HAL

Ross of London six-inch ( 6 inch ) f/6.3 survey lens, on display at the UAS Hangar in Long Kesh.

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A WW2-era design that was widely used psot-war for aerial surveying, frequently fitted to a Wilkinson Ordnance survey camera. Exposures in that instance were onto nine-inch-b-nine-inch negatives.

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Presumably previously fitted to one of the cameras on the Canberra PR.9, but no further information proffered.