The main post office was established at Old Calabar in November 1891; sub-offices existed at Benin, Bonny, Brass, Opobo, and Warri. Initially the postage stamps of Britain were used; in July 1892 they were overprinted with "BRITISH / PROTECTORATE / OIL / RIVERS". A pressing need for halfpenny values in mid-1893 resulted in a variety of surcharges on 2p and 2 1/2p stamps. While most simply read "HALF / PENNY", with a horizontal bar to obliterate the old value, some were overprinted "1/2 d" twice, with the intent that they be bisected diagonally to produce two 1/2p stamps.
The name change occurred just as new stamps were being prepared, and so the first issue of the Niger Coast Protectorate, featuring a 3/4 portrait of Queen Victoria, was inscribed "OIL RIVERS" but obliterated and overprinted "NIGER COAST". Available in November 1893, they were superseded the following May by stamps in a new design and the correct inscription. These stamps continued for the remainder of the protectorate's existence, with a change over to use the "Crown & CA" watermark from 1897 on (the paper had previously been unwatermarked).
The protectorate was established in 1885, and in 1893 was extended and re-named the Niger Coast Protectorate.
The problem is that the OilRiversProtectorate and the Niger Coast Protectorate were administered by the Foreign Office and not transferred to the Colonial Office until 1899.
According to Van Steenbergen the flag of the consul at Creektown, Old Calabar in 1860, was a White Ensign with K in the upper fly, E in the lower hoist and H in the lower fly.