Hi Brian,
Thank you for your response. Whilst the object in the tutorial is certainly is in a Subdivision Surface the Surface is certainly not causing the mesh to collapse on the edge when applying the controlled cuts and trying to dissolve the middle line in “Edge” mode to create the diamond shaped quad.
Take a look at the picture below to see that the geometry, and mesh remains intact and supported by the borrowed edges when the unwanted edge dissolved in point mode.
Before dissolving the point:

After dissolving the corner point:

What I wish to understand is why I do not get the same result when dissolving the middle edge in “edge” mode just like the tutor does it in the modelling tutorial. (See images above.)
I am still hoping that someone will be able to provide an answer here.
Kind regards,
Lucas