Not many of us, surely, can have such a vivid memory since most of us grow up in places that have some multi-racialism about them, places where diverse complexions are the norm.

But when Doctor Orengo (not his real name), an African from Kenya, came to talk to my primary school class in my town in rural/seaside England in 1955 he was as unusual and as exotic as if he was the first Martian we had seen. I was a wide-eyed urchin of 10.

For background, I note that the museum in that aforementioned town (I spent all my childhood there) has just in recent times begun to exhibit a ye olde black and white 1956 school photograph, taken at my school, of a large group of us schoolboys. There are 5o of us boys and "Where are the girls?" the museum is asking on Facebook as, against all the odds of time, it seeks for information from anyone in the photograph who might still be living.

I am in the photograph and have been able to explain to the museum that the explanation for the girl-lessness is that we are a boychoir. We are being photographed because we have just won something (hence the happy smirks on our urchin faces) in our division of the local Eisteddfod.

One of my childhood mates, also in the photograph and alerting me to the museum's exhibiting of it, quips it is a measure of how old we are now that we have become exhibits in a museum, next to and among that museum's rich collection of impossibly ancient fossils.

But as well as there being no girls, there is another startling absence trumpeted by the photograph.

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In this whole regiment of boys, there is not a single coloured face. We are 50 shades of pale. How homogenously Anglo-Saxon we are!

I mention the massed whiteness of the boys in the photograph to illustrate just how exotic Doctor Orengo was, when, the previous year, he came to talk to my class.

Although I cannot remember on what pretext he was given this gig (although I dimly fancy he was a clergyman and wanted to help point us to God) I'm sure his sheer exoticism was the real reason. Perhaps our headmistress thought, correctly, that meeting him would be an education for us.

Whatever the reason, I remember so much about him, the beautiful spectacle of him, the sing-song, bassoon-like musicality of his lovely African voice.

Erudite and kindly, he generously invited questions from us about himself and the planet (for Africa seemed that distant, that exotic, to us) from which he had come.

I was spellbound by him, and hope he forgave my staring (surely our whole class, this time enriched with some girls, stared at him), knowing that there was nothing disrespectful (rather the opposite) about my ogling.

What a powerful memory Dr Orengo's hour with us has etched into this columnist's mind.

When I close my eyes and think of him, he appears in my study in suburban Canberra as palpable as he was on that English afternoon in 1955. When I ask myself in the mirror if there is anything racist about me, and answer in return that I'm not sure but I hope not and don't think so, I wonder about the influence, if any, of Dr Orengo's dramatic appearance in our insular little pommy lives, his blackness as startling to us then as a Martian's greenness would have been.

Like so much about the USA (like so much about life, really) the Mount Rushmore National Memorial somehow manages to be both grotesque and magnificent at the same time.

The memorial has just been in the news because the present, grotesque President of the United States used it, the famous cliff face festooned with the sculpted heads of four US presidents, as the flattering backdrop for his Independence Day speech.

Press and TV framed the President's live and increasingly craggy head and face, in the foreground, with the carved presidents in the background behind and high above him. The comic, cosmetic tangerine of the living President's skin clashed a little with the dignified, sober, stony pallor of the faces of the quiet giants.

I never visit the Booroomba Rocks in Namadgi National Park without thinking how that spectacular granite crag, for so long tragically unemployed, bristles with Rushmore-esque promise.

As the climbing blog theCrag rejoices, the Booroomba Rocks constitute "a large, proud cliff that can be seen from Canberra".

Yes, while Mount Rushmore is a very long way from civilisation (it is in South Dakota), here at Booroomba Rocks we have a site not only a short drive from the federal capital city of our democracy but also even visible from that very city.

Once this project was notionally agreed upon, the ensuing debate about which Australians are deserving of this elite, granite guernsey would be intellectually bracing for the nation. It would require discussion of who and what we are as a people.

My mind is open, but I do see, in my mind's eye, Dr Germaine Greer among them. As well as being a feminist heroine of our nation's intellectual life, her dear face, in old age (suddenly she is 81) radiates a fiercely intelligent cragginess that would lend lustre to the monument.