I mounted the logical volumes, used mount's -B option to bind the /dev, /proc and /sys into the same file system, and chrooted into the directory structure. All worked fine. Suspecting the boot process had an old record of the LVM layout, I rebuild the initrd with mkinitrd. Copying it into place and rebooting brought the whole thing up again, much to his and his partners' delight.
Another successful bit of Linux troubleshooting achieved.
All posts licensed under the CC-BY-NC license. Author Paul Wayper.