No probs, Nigel. Happy to oblige. Yertis agan:

Apropos means "with regard to; in respect of " adding 'of' after apropos is a tautology.

There are two sentences there but you haven't punctuated them at all properly. One just runs into the other, a basic grammatical blunder. To keep your wording, this is how it should read, I'd suggest:

Apropos means "with regard to; in respect of." Adding "of" after apropos is a tautology.

Or a semicolon might have done it after "in respect of," I suppose. Thing is, Nigel, your version is all over the place, not just in the way I've indicated but also apropos of your somewhat cavalier approach to the use of single and double speech marks. One of the "doubles" is actually floating in mid-air. Hope this helps.