The problem definitely exists from the beginning. I have checked a number of times with basic installs of Lucid Beta 1
without installing updates and they all come out with exactly the same output:
DISPLAY=:0 xprop -root |grep NAMES.S
_XKB_RULES_NAMES(STRING) = "evdev", "SKIP", "gb,us", "mac,", ""
So its seems the problem is dormant until such time as the latest console-setup update is applied and re-applies the settings
and then breaks things.