I assume you have seen the RAFM's history of their Antarctic, WE600 ?
http://www.rafmuseum.org.uk/document...-T-7-WE600.pdf
Confusingly, it states:
25 May 51
No.20 Maintenance Unit, RAF Aston Down, Glos (Aircraft Storage Unit). Delivered in glossy silver overall colour scheme with training yellow fuselage and wing bands, Matt black anti-glare top panel and black lettering.
8 Jul 55
To Auster Aircraft Co. for modifications - conversion to a C.4 (Auster Antarctic)
Painted overall bright orange for high visibility.
68
Repainted in trainer yellow, replacing the Antarctic orange colour scheme.
2007
Further refurbishment by RAFM technicians at the MBCC Cosford, including rear fuselage fabric and cockpit door repairs, and repaint into original [sic] overall yellow paint scheme, of which evidence was found during the refurbishment.