Aden, on the coast of modern-day Yemen, used British India stamps until 1937 as a British Protectorate. Canceled Indian stamps from Aden can sometimes be identified with a prominent ‘124’ stamp. Covers to and from Aden that feature British India stamps, especially those involving being posted to or from India itself, are especially interesting to collectors.
British India stamps used in Aden were in Indian currency. 1 rupee = 16 annas, while 1 anna = 12 pies. (This changed to shillings and cents in 1951). Another area of attention from stamp collectors are Aden covers featuring Queen Victoria stamps.
After 1937, Aden began to use its own stamps under the reign of King George VI.