This is one of three examples from DURON (see 6020 and 6023 product codes) where a design was clearly made, but then the application was subsequently abandoned (apologies for the fuzzy picture of the registered application)
This design is also a little unusual as some were painted with the skin colour brown and not black. This is probably one of five or six designs that have the brown skin colour.
Again there is no record in the National Archives in Kew to confirm the submitted design application
Do you have the same wall plaque, but with different markings? Do let me know!