Unusual Graphic 3D Victorian butterfly Brooch RD 169444

An unusual hollow die formed Victorian butterfly brooch with free formed body attached to the surface at the top and bottom of brooch The back appears to be of brass construction with two blow holes and a fold over clasp The wing sections are impressed with a simple graphic shape and a frilled edge as shown - it is difficult to determine the metal used in the construction - my educated guess would be steel with gilded highlights
The registered design number 169444 probably patents the butterfly body attaching detail but I haven't been able to confirm date or maker myself.
Measures 4cm across top of wings and 3cm in length