THE KEY PLATES

In the majority of cases, the stamp colour was fixed across every revenue use. This was purple for values below 1s, green for values 1s and above but less than £1, returning to purple for values £1 and above. However a few revenue uses strayed from the norm, particularly the transfer duty stamps in which a different colour was used for each year.

Although the keyplates were intended for purely revenue use, they were used for postal purposes in British Bechuanaland from 1888 until they were replaced by overprinted British postage stamps in December 1891.