[1] The son of a cotton mill owner called Arthur William and his wife, a vicar's daughter Agnes Louisa, he was born in Didsbury, Manchester, and educated at St Edward's School, Oxford, before going on to study modern history at Merton College, where he graduated honours (second class) in 1897.
He joined the Royal Naval College, Osborne, in 1905, shortly after its foundation, making up for the lack of a textbook by producing his own Sea Kings of Britain (3 vols., 1907–11) and being promoted to head of English and history in January 1913.
[3] A building to house the collection was also soon found when the Queen's House at Greenwich was vacated by the Royal Hospital School, and so in 1934 the government passed the National Maritime Museum Act, making Callender the museum's first director.
The Queen's House was restored, galleries prepared within it, and further objects collected and arranged, all with Callender's energetic participation, and opening came only 3 years after the Act, in 1937.
In his Dictionary of National Biography entry Michael Lewis wrote that Callender: was a man of exceptional personality, a born conversationalist, and a brilliant lecturer, respected and beloved by several generations of naval officers, and possessed of an encyclopaedic knowledge of nautical antiquities.