Good question Ken! Hugh Thompson in Victoria has a fully kitted out Cab 13 ambulance - Jan (of Corowa fame - Hugh's daughter!) are you out there?
At a guess I'd reckon they were unarmed - that's why when hospital ships displaying the red cross were sunk there was always furore because it signalled no arms on board. It'd be some Geneva Convention thing probably.
I have a copy of 'Ice Cold in Alex' - I don't think the ambulance is armed - only John Mills and Anthony Quayle who are blow-ins on the ambulance have weaponry from what I remember. I'll have a look
Cheers Warren