Thanks for the response GLFSTMFIVE.
It is a hidden can of worms really.
I am expected to verify with every company that I freelance for, that I am specifically included in their insurance.
I only freelance occasionally, but for the full-time freelancers, this could be a nightmare.
On the same basis, is it legal for a aircraft operator to allow an "uninsured" pilot to operate their aircraft.
Complicated is not the word.