ELECTROPLATE PERIOD. 1918..1926
Typically Harrison, there are no marginal lines. Electros were prepared from formes of lead moulds. In all cases a new set of moulds were used for each electro. Most printings were made from quad plates.
Die 1, Comb 14 throughout.
The 1½d was introduced as a result of a ½d war tax, which became effective on November 4, 1918. This was the 1st appearance of a new denomination after the intent of replacing all Roo's had disappeared. As such, it is the first use of one of the spare blank dies, intended for just such purpose.
Harrison produced all plates (except E25..28) from a secondary die from one of the 2 remaining blank PB dies. Known as a die 1. Die 2's are from later, steel plate printings.
There are at least 29..32 electros for this denomination. 5a, 6, 6a, 9 and 20 are currently inferred.
Three straightforward colour changes (brown, green, red), but the shades of brown are sufficient to classify at least three genuinely separate shade groups, blackish, brownish, and red-brownish. They are intentionally different. They were intentionally altered in color, by the printer, to avoid confusion with other denominations. Sensibly, ACSC lists them with different numbers (indicating a change of color or paper)