His commitment to freshwater lichen studies culminated in the publication of several comprehensive reports and surveys, which included many descriptions of newly discovered species.

Orange was also on the board of editors at the scientific journal The Lichenologist, and was a member of the editorial team for the Lichens of Great Britain and Ireland series.

[2] In this work, published after his death, he was described by his coauthors as "a prolific author and a world-renowned specialist in the Verrucariaceae, combining expertise in molecular phylogenetics with meticulous morphological observation.

Beyond his scientific contributions, those who collaborated with Alan benefited from his keen observational skills, wide species identification capabilities, and the meticulous detail he brought to his work.

Those who interacted with Alan remember him not just for his prodigious knowledge but also for his unique humour and willingness to assist in navigating complex taxonomical challenges.