Wearing My New Sporran

[cavscout]

How long is the flap attached to the one keeper? It appears to be about the width of a typical waist plate buckle.

Based on belts I've done in the past, the leather flap on the one keeper is probably intended to be behind the front belt buckle. It could be to protect the kilt from rubbing against the buckle prong or it could be simply to give the appearance that the belt runs continuous around your waist. As has been said, the keepers are intended to secure the folds and frame the buckle. This fastening method is very common on military dress belts. Just a way to make "one-size-fit-all". Most belts today have one side fixed with rivets so truthfully you only need one keeper, but symmetry is usually more appealing.