So, I finally got round to putting my new SSD in my MacBookPro5,1. It wasn't without incident, but I suspect that was my fault. My intention was not to do a clean install, but just to install the SSD and clone back to that drive. So, I did ...
1. Backed up (cloned) my HDD using CCC, to my external USB drive. This was my normal backup method anyway.
2. Built the installer using the patcher onto the external drive. I only really did this to be able to run the post-install patches - wasn't actually sure if apfs patch was the only one I needed to apply.
3. Put the new SSD in the laptop.
4. Initialised as APFS.
5. Cloned the backup back to the SSD using CCC.
6. Ran the post-installer to apply the apfs patch, as well as all the others recommended.
7. Booted, got the scrolly text thing followed by the prohibited symbol. Crap.
So, I tried a number of steps to try and work out what was wrong, including installing a bare HS to see if the SSD was faulty.
Anyway, to cut a long story short, I believe my problem was related to the initialisation of the SSD. What finally worked was to Show All Devices in Disk Utility, and initialise from the topmost level. I daresay this has been covered somewhere in this thread. I'm not really sure what I did first time but it certainly didn't work. I think, after the clone onto the SSD, that I ended up with 2 containers. If I were doing this again, I'd be tempted to initialise the SSD as HFS+, and later convert to apfs.
Observations so far.
I had to re-activate my copy of Office 2011 because my existing key didn't work. What's more, I had to do it over the phone because the server was "temporarily" available. Seemed like a hell of a coincidence? Maybe it's permanently unavailable now.
Booting is as slow as it ever was but once booted it seems snappier.
I've always had the double boot (double chime) issue, and I now was getting a double chime and double scrolly thing going on. So, I followed the advice in a post way back to delete the Firmware.scap file from the /Volumes/EFI/EFI/APPLE/EXTENSIONS directory. What I see now is quite a long empty grey screen of what seems like about a minute (no Apple logo) before the boot process proceeds. I don't know if that's normal. Maybe
@dosdude1 could advise.
That's all of note so far.