This was a 1d red stamp featuring a slightly crude design depicting Queen Victoria.
This was a key type stamp depicting Queen Victoria, and it was printed by De La Rue.
Postage stamps, both of the Leeward Islands or Montserrat itself, were also used for fiscal purposes.
[1] Colourless or purple impressed duty stamps were used in the late 19th and early 20th centuries.
This practice was discontinued long before the 1970s, and very few issued examples of these stamps seem to exist.