Does it have the pleats sewn in, or is it just a big piece of tartan yardage, fringed at both ends?

There are various approaches to putting on the long plaid. (In the military certain officers and sergeants wear them with certain orders of dress, not just pipers.)

They're all the same in that you have to end up with the thing wrapped snugly around your body, under the right armpit, both ends going through the epaulette on the left shoulder, with the end which comes from your right armpit across your front and up towards your left shoulder going over the other end through the epaulette on your left shoulder, and hanging long down behind, usually ending around where the top of your spats or hose are.

The question is what to do with the other end, the shorter end, the end that goes from your right armpit across your back and up through the epaulette on your left shoulder, underneath the long end of the plaid.

You see old photos with this short end just left dangling down in front. But usually in the military it's hidden by some means. I've tucked it under the part of the plaid that goes across my chest. In a band I was in years ago, we took the left-shoulder shell off our doublet, and twisted that short end of the plaid and formed it more or less to the shape of the missing shell, tucking it in somewhere (I forget just where). The old guy in the band had served with the Cameron Highlanders in WWII and presumably had got this method there.

All this stuff is easy to demonstrate but difficult to put into words.

But anyhow this is what it needs to end up looking like:





Note that the leading edge of the long portion which hangs down behind is brought forward and pinned with the brooch.