He was English master at The Leys School, Cambridge when Lowry attended. He was a master from 1889-1924. Educated at Kingswood Scool and a scholar and prizeman of Wadham College, Oxford. He had an "extraordinary memory and knowledge of any man I have ever met. He was a classic, mathematician and English man of great resource and teaching power, if a boy wanted to be taught. He was a light versifier of merit and wrote for Punch and other journals." J.H. Hays quoted in Derek Baker's book on The Leys; Partnership in Excellence. He also acted as a referee for Caldicott School which Lowry also attended in preparation for the The Leys.
He wrote many books including Story of Myths 1927, The Northern Saga 1929, The Whirligig of Taste 1929, Fashion in Literature 1931, Story of Religions 1934 etc. He appears to have had connections with several literary figures during the 1920's and 1930's including the Woolf's as he had work published in their Hogarth Press. He also had links to the magazine Life and Letters.
He lived after retirement at 5 Woodville Road, Blackheath. Lowry spent several months in Blackheath being tutored by Kellett for the entrance examination to Cambridge between 1927 and 1928. Kellett had considerable knowledge of Scandinavian mythology which may have have been an influenced Lowry who was already obsessed with Norway. There is also a possibility that Kellett introduced Lowry to modern Scandinavian literature by Bang, Hamsum, Jensen and even Grieg. The link, as yet unconfirmed, being that all the novels were translated by A.G. Chater. Another interesting link is that Kellett wrote a book Literary Quotation and Allusion 1933, a subject matter used to great effect by Lowry in his work.
Lowry refers to his time with Kellett in his novel Under The Volcano when Hugh recalls; "He was already entered at Cambridge for a year or so hence. He had not, however, the slightest intention of going there. The prospect of it, for some reason, he dreaded only less than being stuck meantime at some crammer's. And to prevent this he must act swiftly." (Pg. 160).