Final answer:
Miranda's choice of partner is not mentioned in the provided information.
Step-by-step explanation:
Margot and Juliet work as secretaries at the War Office. Margot works with Admiral Mark Kerr on the Air Board, while Juliet works with Colonel Williams on Military Railways. Since the question asks who Miranda picks to work with James Holt, the provided information does not give any indication as to who Miranda chooses to work with. Therefore, without further context, it is not possible to determine who Miranda picks to work with James Holt.