So, after my dilemma of the spinning wheel stud on Saturday, I decided there was only one way to resolve the issue and that was by very carefully cutting in the wheel nut with an angle grinder. Obviously, the hub itself is knackered as well, so I now had the job of removing the brake callipers, brake discs, etc on both sides so I can replace the hubs. (I've opted for upgraded alloy ones from retro Ford.)
So, once again the car was jacked up and placed on axle stands (I think it's spent more time in this position than it has driving on the road!) I removed all of the nearside hub first as I was waiting for it to get a bit later in the morning before I started getting noisy with the grinder.
I used the air grinder first of all to cut into the wheel nut but had to move onto the electric grinder in the final stages. It did put up quite fight, but in the end, it was no match for my perseverance. (As you can see below)
With the front wheel finally off, I was able to remove the front brake calliper and front hub in readiness for the newly ordered parts to arrive. So, the Green Cortina has now reverted back to what seems to be its natural position. I.e. In the garage, up on axle stands!