7/03/2012 Straits Settlements
The idea of simplifying the printing process when producing similar runs of printing designs for a wide range of colonies was created by De La Rue in 1879. Their printing process split into two: the design of the printing plates by producing two individual plates, a key plate (or head plate) for the bulk of the design, and a separate duty plate for the name of the colony and the value. These are often known as key plate stamps.
While key type stamps are always of one colour, key plate stamps are bi-coloured. This method has the advantage that most of the design remains the same in each of a stamp series, with only the value, name and colours changing. In the case of the two stamps above the frame and value (the duty plate), these remain the same, with only the central portrait of the king being changed.