Now offer three weeks the nurse has said I can keep the dressing off and let the air get to it. The sore has turned from red through blue to now a very dark almost black colour. Evidently it will now behave like a scab and dry up and drop off with new growth on my heal under it. Had it become infected it could have just become a mass of dead and decaying flesh! Not a thought I wish to dwell on. I made the mistake of going on Google images and some of the pictures are horrific, not a thing to do if you have a weak stomach.
It could be several more weeks before the black scab finally disappears if anything changes I will keep you posted.