I've been on the phone to Chrchills this PM. The chap I spoke to confirmed I have basic 3rd Party insurance when driving my daughters car - even though the car does not have its own insurance. I've asked for an email to confirm this, which they said they'd provide. I haven't received it yet although to be fair, maybe that email gets provided by a 'typing pool' functional area rather than the policy inquiry dept.
Its so kafkaesque, maybe they don't know themselves.