I managed to get the Air uninstalled - took a couple of reboots
before I managed to find it in Synaptic ...

Went to the [TD] website and told to install ... asked if I wanted to
install Air first ... yes please ... all seemed to install ok,
launched, then threw up a dialogue saying that this was "one of a
small machines" Air is unable to run on, and they're working on it (or
something like that - I didn't make an exact note of the wording - too
busy swearing at it ...).

More reboots & uninstalls later, back to square one ...