The age of the box and the 'esquire' suggests the gentleman to have been of a higher rank,
and this suggests the J.Longden to be The Clerk to the Privy Purse.
Nevertheless, as the letter shows, both worked at Buckingham Palace.
A Victorian leather hatbox from Buckingham Palace c1869-80
Engraved J.Longden Esquire and with accompanying letter from Buckingham Palace.