St Thomas was a hub of the West Indies packet service from 1851 to 1885. Initially mail was transported by a Spanish packet to and from Puerto Rico; but in July 1867 the British picked up the mail contract, and packet letters are known using British stamps as late as 1879. 1874 saw the first numeral issues of the same sort as used in Denmark. Values ranged from 1c to 50c; all were bi-colored. Inverted frames are common for several of the lower values. A definitive series of 1907 depicted Frederick VIII, followed in 1915 by a series for Christian X.