Kenneth Scudder, "Queensland Postage Stamps 1879-1912" published in 2013, has brought all these threads together. His research has indicated that the first printings in around May 1880 were deep mauve and mauve. Note that this contradicts Basset Hull who believed the first printing was in 1881. Scudder believes that there were two printings with an estimated 62,670 stamps issued for postal use.
Regarding Basset Hull's 1881 issue, Scudder notes that between May 1881 and the end of the issue in February 1883, 138,740 stamps were issued for postal purposes and that there were probably four printings. The first printing was deep reddish violet which was very close to the colour proofs approved in April 1881. The shades then became progressively paler, turning from violet to lilac and that one of the printings in the reddish lilac has a somewhat spotty appearance. Scudder contends that the last printing was probably the pale reddish lilac.