They're listed as an option in the 1956 Brown Brothers catalogue, but not in the 1952 edition.
Neil Foddering Weymouth, Dorset, England
>From: "Peter Brueggeman" <pbrueggeman@ucsd.edu>
>To: <classicrendezvous@bikelist.org>
>Subject: [CR]re: anodised airlites
>Date: Sat, 9 Jun 2007 13:30:27 -0700
>
>Regarding John Hudson's query ".... approximately when the anodised
>versions were introduced?..."
>
>Holdsworth's Aids to Happy Cycling catalogue lists coloured flanges for
>British Hub Airlite Continentals as extra in 1957, and doesn't list this
>hub option in 1955 and 1952. Appearance in a catalogue isn't the same as an
>introduction date, of course.
>
>Peter
>......................................
>Peter Brueggeman
>La Jolla California USA
>pbrueggeman(AT)ucsd.edu