RAF OR cap badges can they be dated?

[SAS1]

The black buckles, buttons and badges were intended for TSD only with the gold cap badges and flight sergeant crowns being for the blue service dress (Ive never seen the buttons). In the event most of the black did not start appearing until about 1943 by which time the numbers of personnel were vastly reduced in tropical climes. The result was that they were instead used on the blue uniform, although regardless of blue service dress or Tropical Service Dress, the blue headgear was worn with both.

[arrestingu]

...I have a full set of RAF 1918 buttons spare in my collection, thus for sale and a pair of RAF cuff eagles 1918 also for sale ,if interested drop me a line ..thanks steve