Prototype 40 - Goldplated Damier

Normally this Damier pattern is found in sterling silver or vermeil (goldplate over sterling) and marked accordingly.  This version is only goldplated over brass making it quite unusual.

Did Parker make this after the normal production models in an effort to find a less expensive alternative?  Or was this made prior to the production of the Damier, to be a mock-up of the vermeil version?  If you have some Parker documentation that answer these questions send me email.