Without wanting to highjack Jon's lovely painting thread.
The arm band was worn with a uniform(if your unit managed to get a uniform before they were renamed.)
There's also an evolution to the square arm patch .'Home Guard 'Arm bands were issued and often folded in half and stitched directly to the uniform.
This issue was in turn replaced with the cloth badge. It's simply a case of just how far down the resupply roster your unit was. The further down the more likely you were to be issued the newer kit.(the logistics being as you equip you run out of batch A and the new batch B starts straight on the tail of the first and you continue down the unit issue until all units have kit . Then the final design becomes the resupply for all units.((occasionally you can get kit ahead or out of issue order if your in with QMS .)
So your Grand father was right.As far as the regs go . But regs are often seen as more of a guideline(until your caught

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