The story
In August 1976, Bryan Ansell co-founded Asgard Miniatures with Steven Fitzwater and Paul Sulley in Nottingham and became its lead sculptor. Ansell was an experienced sculptor, having previously worked at Conquest Miniatures. Ansell left Asgard Miniatures in February 1978 to form successful rival Citadel Miniatures with funding from Games Workshop.
Less than a year later, in December 1978, Citadel Miniatures was started by Ansell/Games Workshop, as announced in White Dwarf issue 11:
Games Workshop and Bryan Ansell have got together to keep-alive Citadel Miniatures, a new miniatures company that will be manufacturing several ranges of figures. Ral Partha are already in production, but Citadel will also be producing own ranges, including the Fiend Factory figures, Fantasy Adventurers and Fantasy Specials. Citadel will not be limiting production to SF/F figures, but also new ranges of historical wargaming figures.
The following issue of White Dwarf contained the first advertisement for Citadel's forthcoming figures.
From Wikipedia’s article on Citadel Miniatures, shared under CC BY-SA 4.0.3