Credit where credit is due. I don't know if anyone has been following this but I rather missed the fact that the (excellent) spaces.microchip.com was being closed down by Microchip to the point where I thought I had completely lost access to a fairly extensive SD/MMC bootloader project I had been storing and version managing there.
I even posted a fairly derogatory (but hidden) thread in a moderator forum here expressing my irritation. The suggestion (thanks Morten) was to "open a support ticket".
"Yeah, right, that's going to work" was my initial, rather cynical thought.
But I did it anyway and had a dialog with a Microchip/Atmel support engineer called Sanjyot.
Well I have nothing but admiration and praise for the most excellent support I got (and in a very timely fashion). Microchip have unlocked the project I could not access so I have a final chance to move it over to www.github.com/wrightflyer/
So this is a big vote of thanks for everyone at Microchip who was involved in resolving this. It restores my belief in human nature!
(BTW what was doubly irritating was the fact that something about spaces.microchip.com (formerly spaces.atmel.com) meant that web robots could not access the pages so the Way Back When machine, that I would normally have relied on to find something "lost" from the internet, never managed to get a successful snapshot - guess I'm also becoming too reliant on the "Internet Archive").