In 1938, Oldaker was appointed as Precentor of
Christ Church, Oxford, a role which included serving as Master of the
Christ Church Cathedral Choir School. He arrived there in September, quickly gaining the nickname of "Pip", believed to have been inspired by the name of a
Daily Mail cartoon strip called "Pip, Squeak, and Wilfred", in which Pip was a dog. He made big changes at his new school, joining the
Incorporated Association of Preparatory Schools, which meant that all boys had to be prepared for the
Common Entrance Examination. He began to appoint boys as prefects, which was new, and he also divided the school into houses, called Wolsey, Aldridge, and Carroll. He introduced the teaching of
Ancient Greek and changed the name of the school slightly, insisting that the word "Choir" was not needed. In December 1939 he launched a school magazine called ''The Cardinal's Hat'', including news of old boys. The greatest change he made was trebling the size of the school. On his arrival, the number of boarders was only nineteen, but a year later it was thirty-four, and by 1943 there were sixty-eight boys altogether. Oldaker was resisted in this enlargement by the Dean and Chapter, who did not want a larger prep school on their hands, but he was able to make use of the time-honoured prerogative of the Master of the school to be allowed to take private pupils, in addition to the Cathedral choristers. Oldaker married Margaret J. Dickson in Oxford in 1941. One of the boys Oldaker taught at the Cathedral School was
Crispin Nash-Williams, whose biographer has said that he was a formative influence on Nash-Williams. In 1945, Oldaker moved on to
King's School, Canterbury, accepting an invitation from Canon John Shirley to take charge of the junior school, Milner Court, at
Sturry. One reason for the move was believed in Oxford to be that the Dean and Chapter of Christ Church were giving him little support in his ambitious development plans. In 1946 Oldaker wrote to
Country Life from Sturry about the
tithe barn there, which was 160 feet long, asking "And can anyone tell us where the largest tithe barn is?" The editor replied that this was "the gigantic barn at
Abbotsbury, 276 ft. long." While at Sturry, Oldaker and his wife lived in the manor house until moving into a cottage in the grounds, so that the main house could be used to expand the school. A history by D. E. Edwards comments that Oldaker achieved a lot while there, concentrating on the academic and musical sides of his school, while not neglecting games. In 1956, he retired from the world of education, to become a parish priest in Devon. ==Later life==