10 Shillings

Australia's Note Printing Branch in Melbourne took over production of this series from the British-based printer Thomas De La Rue following the Commonwealth Bank's decision to establish full domestic printing capability — a shift that was as much about institutional confidence as it was about logistics. The transition was not entirely smooth; early Melbourne-printed notes showed minor ink consistency problems that De La Rue's equipment had not.

The Riddle-Sheehan signature combination dates the earliest issues to 1936, when Ernest Riddle held the governorship. Sheehan's name then carried over into the 1938 pairing with Armitage, making him the sole continuity figure across both signature varieties of P#21.