In the National Archives there’s a copy of “Mosquito Mutterings,” (not sure it was ever distributed,) a Prune-style collection of how-it-should-be-done cartoons, and the flyleaf states, “Published by The de Havilland Aircraft Co. Ltd., England 1943,” which would seem to indicate they always used the lower-case “d” themselves.

It’s all too easy to claim “There’s no evidence,” but this needs the counter, “where have you looked?” (And this is not a personal attack.)
If you want to find anything in the National Archives, it often pays to get very inventive, for example, looking under “Hurricane” is likely to be a complete waste of time, since the aircraft didn’t get its name until after the second tender was produced, and accepted. Up to that time it was officially known as the “Hawker High-Speed Monoplane,” not “Fury Monoplane,” as is often reported (it might have had that name in Hawker’s circles, but not the Air Ministry.)
The files (if they exist) from the NPL would be the best starting place, but that assumes they’re filed under an obvious title; more than once, I’ve found that I’m reading Farnborough’s files, but the only clue comes from the name(s) appearing in the paperwork, since the file is usually titled by its subject matter, not the originator.
The information could be anywhere; remember that files are received, and annotated, by civil servants, many of whom won’t have the slightest interest in (or knowledge of) aviation, and then lie “fallow” for 30 years, before they become available for nosey people, like me, to ferret through.
In my time, I’ve found a scale drawing of the Spitfire in a file on camouflage, papers (obviously misfiled) on Lancaster bomb doors in a Hurricane file, and (only yesterday) reference, in a Spitfire test report, to some Rotol propellers having “armoured” leading edges.

I checked all the ORBs, today, at Kew, and all squadrons were involved with air firing, at Ipswich, on the dates you listed..
Edgar

Scale Models/M.A.P./Nexus did a set for the late Spitfires; My hobby Store still advertise them, under “modelling line drawings,” and the original reference 3006. Possibly a better bet, but not yet ready, Arthur Bentley is in the process of doing the full set of Spitfire drawings.
http://www.myhobbystore.co.uk.

THANK YOU!! The point I have been repeating ad nauseam in various threads for more than a year, but it never seems to provoke any comment or response.

In politics, there’s no such word as “can’t.” If there’s any chance of their gravy train leaving the rails, some way to “renegotiate” will always be found. Cynical? Who. me?
I’m just an ordinary mug, who saw “Broon” and his mob do away with the 10% tax band, so that everybody lost the same amount, but those on low income (like pensioners who were daft enough to take out private pensions) lost a greater percentage of their income.
Now, the latest shower have not changed the tax bands, so, out of a £5 pension increase, I immediately lose 20%, and, yet again, I see the “apathetic” jibe trotted out as an attack on those who won’t vote; certainly, there are those who can’t be bothered, but there are also huge numbers who loathe politicians, as a breed, and would dearly like to find someone (anyone?) remotely interested in the peasants of this nation.
Go ahead, make voting compulsory, but add a “none of the above” box to the form, and lets see how many votes that “party” gets.

A small, portable (pocket-sized) tape recorder could be useful, too.

It’s a pity that someone, in the police force, didn’t think to ask “disgusted of Attleborough” a pertinent question, before getting the full majesty of the law to creak into action, and that would be, “Are you a Christian?”
If the answer is no, then he cannot believe in Heaven and Hell, so how can he get upset about a “threat” to send him to a place that doesn’t exist? To take it a stage further, only Christians are likely to believe in the existence of Hell, and, since they believe, they won’t get sent there, so where’s the threat?
Once again we have the law made to appear an ass, because the world is full of people who insist on getting offended on my behalf, when they could actually be trying to do something useful.