No, we’re not delving into the world of the camera obscura, this is what I’ve been cutting out.
The key to success is to change the blade immediately you feel a drop in performance. This is usually more force required to achieve the same cut. Failure to do so invariably leads to slipping of the blade with the extra pressure exerted, much swearing, and starting again.
Fortunately in this case, I was on the ball, noticed, and changed the blade before anything untoward happened.
So now the cab window apertures are cut out, glazing material cut on the guillotine from an offcut from a Metcalfe building model, and the doors cut out ready for the second side to be stuck behind to create the illusion of depth.