Answer November 2020

The fleur-de-lis adorns the archway that is to the west of the Old Grammar School, and is visible as you walk up or down Wentworth Place.

The fleur-de-lis is also replicated on a pillar by the stone wall to the front of the building, and the pictures above show the front and rear views of this pillar.

Thanks to Stefan for the spotting this, and to Stefan and MarkRG for the photos.