The Last Secret Patent
The public records that give details of inventions belonging to the 1960s are just beginning to be opened at the time of writing. The last secret patent could be one that is described in a file that is closed until 1994 (PRO: ADM1/22169). This is already indexed as being about the patents of C. C. Mitchell, an aeronautical engineer who had a number of secret patents concerning the hardware used in the Second World War for catapulting aircraft from ships (PRO: ADM1/13839). An example of his work is described in the specification of BPN 649180, which was applied for on 11 October 1938, but not published until 17 January 1951. Apart from the long delay in publication, this specification is not particularly interesting.
The records show that there have been hundreds of secret patent cases since the first case we found in 1855. For most of these cases no technical detail survives, only a record of some agreement. For example, there is a copy of an agreement between one Isaac Francis Taylor and the Admiralty, dated 5 November 1915, according to which Taylor was to produce a full description of his invention, which was 'portable and, in any weather, destroys aircraft of any type which come within a clear range of 25,000 feet' (PRO: TS21/67). Once the Admiralty was satisfied, they were to pay Taylor, £500,000, and he undertook to 'obtain and assign to the Government a secret patent for the invention'. The Zeppelin raids on the City of London in September 1915 had caused damage well in excess of £500,000, so Taylor was not setting the stakes too high. Who he was and what hardware he had in mind is not known. It would be possible to cite many such cases from the early nineteenth century up to the present day.
This brings us back to a point that was considered at the end of Chapter 5 and again at the beginning of Chapter 8: the enthusiasm of some men for applying their technical knowledge to war. I make no apology for having frequently referred to an inventor as