Band of British Army regiment hard to follow (4)

I believe the answer is:

sash

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'band of british army' is the definition.
'sash' can be an answer for 'band' (a band of material). I'm not sure about the 'of british army' bit.

'regiment hard to follow' is the wordplay.
'regiment' becomes 'SAS' (Special Air Service).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'to follow' says to put letters next to each other (some letters go after or follow others).
'sas'+'h'='SASH'

Can you help me to learn more?

(Other definitions for sash that I've seen before include "Style of window" , "Decorative belt" , "Part of a window - decoration" , "Brown bread for waist or shoulder" , "Cummerbund" .)

I've seen this clue in The Telegraph.

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