This is surely not just negligence. It looks more as though operatives of the Tory governments of prime ministers Cameron and May are on a mission to sanitise Britain's colonial past:
"Thousands of government papers detailing some of the most controversial episodes in 20th-century British history have vanished after civil servants removed them from the country's National Archives and then reported them as lost. Documents concerning the Falklands war, Northern Ireland's Troubles and the infamous Zinoviev letter - in which MI6 officers plotted to bring about the downfall of the first Labour government - are all said to have been misplaced. Other missing files concern the British colonial administration in Palestine... " (Government admits 'losing' thousands of papers from National Archives, Ian Cobain, theguardian.com, 26/12/17)
Nor is this new - see my 6/8/16 post Too Many Skeletons in the Cupboard.
Since we may well be witnessing a cliocidal campaign here, a commission of inquiry would seem to be in order.