My only advice would be - Don't imagine for a moment that there are any hard and fast rules about these items. There is certainly no overall policy to which the constituent parts of the British Army adheres.
As an example - both the attached were designed by me (and locally sanctioned by D Int Corps). The officer's slide as worn in Hong Kong and the other was exclusively for OCdts of Int & Sy Gp (V) (now 3 MI Bn (V))
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