Metal sliders

[Mike H]

Can anybody throw any light on something for me.
In my collecting i have a few staybrite badges that have a metal slider fitted rather than an a/a one(Manchester Regt,Northamptonshire Regt,RA beret).The joint between the two appears to have been flattened thus holding it in place.Where these some of the earliest produced badges ? Had the manufacturers not found a suitable way to affix the slider ?
Any input would be greatly appreciated.