Swing mounted is as it says - the medals swing. And bash into each other. As a child I can remember parades and only hearing the CHING, CHING, CHING as the troops marched along. For parades and such - no problem. In fact it probably helps the troops keep time.

But, when there was a Dining-In Night or formal dinner the noise could be quite load and distracting.

It started with the miniatures (for formal or Mess Dress). The medals are in fact sewn down to a board so that they cannot swing. They also have longer ribbons which fold over the back giving a backdrop to the medal (no gaps for uniforms to show through)

These are mine:



See how the ribbon forms a backdrop.

In the UK, they very soon went over to court mounting for all ranks, full sized and miniatures.