As a means of efficiency when building a Georgian Colonial cottage like the one pictured above, the original mason would have used off-cuts and remaining units which didn’t make the cut for inclusion in the dressed building front facade.
This ensured a quicker turnaround in construction by focusing on the architectural ‘viewpoint priority’.
That being said, you can also use traditional ribbon point to convert a random rubble stone wall into ‘square dressed’ ashlar. Not only does this method correct any cracking but it also cleans up the appearance of the wall to correlate with the dressed Georgian front facade.
You may also notice the removal of the render in the jambs of the window and door.
Render removal is a delicate process and is one done without machining. If you were to take a grinder to the render in order to remove instead of using a chisel or small bolster, you’d run the risk of removing, also, the tooling left on the jamb by the building mason.
After discovering the tooling, the chisel direction in removing the render correlated with the chisel direction of the tooling underneath. This further protected the detail.