Royal Signals post 1946 on blue cloth backing

[sapper533]

You'll probably never find the answer if it was unofficially done unfortunately.......but I wonder if it might have been worn on the 'orrible GS cap ....the khaki beret type thing worn during the war, there are many examples of unofficial coloured backing sworn to the badge to brighten them up.
Here's my REME example, I also have an RAMC version, maybe as blue was the backing colour for pips blue was chosen. The backing plate being perfect for the shape required. But who knows.
Apologies for the quality of the picture.
Happy hunting
Sean