"It is not allowed to smoke here"

Thanks a million, Lordyaswas.

I've read this now, and very interesting it was. I think I agree with Contrex that it is correct, and with the Americans who think it sounds a little awkward.
Canadians too, sorry.
For some reason I was reminded of the sentence
“It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife.”
But I wouldn't employ Jane Austen to write me a no smoking sign.

I think it's the use of the infinitive (to smoke) which makes it sound awkward.
We might better say:
Smoking is not allowed here. Otherwise
You are not allowed to smoke here
or even
It is not allowed for you/anyone/people to smoke in here

I've seen exactly this sentence on a sign in a gateway in Corfe Castle, but couldn't relocate the photo...

Well there you go then. Perhaps Jane Austen wrote it.

Or Thomas Hardy.