One of my favorite lessons is about standing still at the mounting block: https://www.montyrobertsuniversity.com/training/2031189059

Thanks. I've watched the various lessons but all require a 2nd person. He will stand if someone is at this head but this is not practical on a day-to-to day basis as I am on my own. To reiterate, he will stand at block, I can lean over saddle, pat all round him but as soon as I lift my foot to stirrup he steps back.  After several schooling and repositioning he will stand.  It is not an issue when I get off at end of schooling session and remount only the initial mount. 

viv-lynch

If you could just get someone to help just one day for about an hour that would help solve the issue.
I had the same problem once and I mainly work alone but this day I had one of my granddaughters come over to help out.
We actually followed Monty's instructions for the entire session. (about an hour) I took the dually out front and my grand daughter stepped on the block. We did as Monty does in the video. With my grand daughter walking up to the block, rubbing an scratching about a dozen times. Then when she tried to put her foot in the stirrup he moved back. I schooled him with the dually and Monty says in the video I watched "If a horse won't stand still at the block, then he needs to back up" Which is what I did. It only took 3 times schooling and backing to get him to calm down and relax. And getting him to relax, to me, is the key. Honestly I truly believe most all horses will relax and calm down after they gain your trust and see you doing the same. Being relaxed. 
I do understand the problem and I especially understand being alone and trying desperately to work with them. I am with all mine (5) daily and also  I work with other horses that have minor behavioral  issues, generally by myself and alone.
The biggest thing I have learned since joining the UNI is that there is always someone to jump in and give advice to help out. That is a tremendous asset.
I hope this does help some.
Connie Mack

Connie,  He is backed up but I will try again with the Dually on. At the block he is calm and relaxed to the point of having his eyes half-closed, sighing and yawing. 

 I have 3 Tennessee Walkers.  I've never actually trained one but I truly believe  they are bred to go as soon as the foot hits the stirrup. When I bought them each one had the same problem you are having, but a little more severe. I had to take the left rein and pull their head towards me just to mount or they would immediately take off with me. When I started working them with the dually, I would use it instead of the bridle. I schooled them backwards when I was mounting if they moved even an inch. It took me several times to get their attention but it did work to the point that they would stand still, at least until my rear hit the saddle. Then off to the races. (My other problem) Eventually I did manage to calm them all down enough to mount with full gear with little or no problems.
I really don't know whether it's repetition, trial and error, hard work or all three getting them to totally relax with me mounting. I just know it took time, but time well spent. I have 3 of the calmest and most generous pleasure riding horses now that all my grand children can ride safely.
 I guess I'm trying to say to use the dually while working with him. It worked for me and it is the best tool I have ever used for training purposes.
The horse I had mentioned in my first message to you is a Quarter horse that the previous owner had tried to train for barrel racing and had actually abused the horse with riding crops and whips.
Again. I understand your situation and hope you can stick it out with him long enough to help him and you.
Connie Mack

Here's another version of the Mounting Block training https://montyrobertsuniversity.com/training/2031188578