This is only a partial early British frog,  it is not know if it is part of a shoulder belt or would have had just a belt loop in much the same style as modern bayonet frogs.  The scabbard which it contained would have been a rear stitched scabbard with front frog stud,  such as the scabbard example illustrated earlier as c.1750.

It was found with a Pattern 1784 scabbard in it,  however as this scabbard is front stitched it is unlikely to have been correct for this frog.