To make the point that the Long Plaid shouldn't properly be called a "piper's plaid" here you can see that all the officers of Highland regiments (kilted or not) wore them, and there were a lot more officers than pipers.
And- say it ain't so- a piper of the 79th Foot (Cameron Highlanders) wearing a belted plaid (as worn by the officers in Full Dress)
Long plaids were very popular in Victorian civilian Highland Dress, often just draped around the body, less often with a brooch.
Belted plaids were also popular with Victorian civilians
As we know Highland Dress was mostly scrubbed of accessories between 1910 and 1920, making plaids of any sort much less seen.
You have to have a stellar reputation as a piper to get away with wearing all that stuff!
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