Thanks boys,
A hypothetical conversation became rather embroiled over a few beers over a couple of the situations above (many are pretty self explanatory obviously).
Your answers above are just what I needed to settle the argument, as I do not have any handy reference texts as 'proof'!
No, not a thing for sub FLs in the tropics of course, although a swarm of locusts might block the odd pitot!
Although as you well know it has caused a few a/c to come to grief. Wasn't there a 727? that crashed due pitot icing in the US? That was the instigator of said conversation.
CS