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

You'll struggle to find a dictionary that gives examples of usage that doesn't include an example using "apropos of." It's a perfectly good construction. In fact, "of" is usually required. Oh, and by the way, Nigel, that last bit of yours that I quoted there is far from being a good construction. In fact, it's illiterate. :-)

Another Shaw tactic, claiming a sentence is illiterate without giving a reason.