The very last files that the UK National Archives plans to digitalize and put on line won't be the ultra-secret Ultra files . Trust me : Ultra was a success.
No the very last files, if ever, to be digitalized and put on line will be the series FO (Foreign Office) 370/926 : requests from aboard , 1944-1945, for that wonderful British invention , penicillin.
That's because what should have been the greatest success for the UK in WWII turned out to be their worst total balls-up disaster.
The British didn't have any penicillin : not really enough for their own troops and civilians, let alone to address distressing appeals coming from the dying all over the world.
What should have been a signal triumph as Britons freely gave to the word the greatest medical boon it had ever known - would ever know - instead became an opportunity for America to practise "penicillin diplomacy" and replace Pax Britannia with Pax Americana.
The British Empire actually fell, not in early 1942 with "The Fall of Singapore" , but in early 1944, with "The Penicillin Shortfall Crisis".
The cause of the failure was the usual one : leaving policy in the hands of scientists, instead of the politicians.
Stupid and venal as the politicians often are, they know a political minefield when they see one - but by the time they saw this one, it was just too late.
Just as the families overseas were forced to bury their dead when the British failed to help - so too, the PRO and UK archivists will bury these embarrassing files : but good....