One of the most memorable things about Bob Diamond's three-hour testimony before the Treasury select committee was not, unfortunately, the inside story of how Barclays diddled Libor, but the bank's former chief executive addressing the MPs by their first names.

So, the MP for Hereford and South Herefordshire was not Mr Norman but "Jesse". Andrea Leadsom, a Conservative MP from the 2010 intake who so electrified the hearing that, for some Tory MPs, it stirred memories of a young Margaret Thatcher, did not look impressed. A former Barclays director herself, she got under Diamond's skin by suggesting he should have known what was going on. But Diamond responded by using her name over and over, once several times in a sentence. He luxuriated in every syllable: "An-dre-a," he drawled through his capped teeth.

Clearly whoever had prepped him thought using first names would encourage the MPs in return to call him "Bob", and therefore go a bit easier on him. This is a strategy vividly spelt out in an episode of The West Wing, in which Jed Bartlet's chief of staff warns that the president must not meet a foreign diplomat and suspected terrorist who is in line for assassination later. Leo McGarry says: "I don't want him putting a voice to the guy. I take my daughter to a seafood place, the first thing she does is name all the lobsters in the tank so I can't eat 'em."

Diamond wanted the MPs to name their lobster so they wouldn't have him for breakfast. But they refused, calling him "Mr Diamond" – although their questioning didn't quite live up to a grilling: they merely showed the lobster the pan.

This habit of over-familiarity is not confined to the high-living Americans who run our banking system. I cannot count the number of emails I receive from PR people I've never heard of which begin "Hi Jane". This, usually paired with the forced cheerfulness of "How are you?" from someone who doesn't really want an answer to that question (what if I replied, "Got a bit of a scratchy throat, actually, and my washing machine's on the blink"?), is one of the irritations of modern life. Rather than persuading me to read on, they make me want to ignore their emails.

More seriously, there's an epidemic of over-familiarity in our hospitals. A report by the Care Quality Commission last week warned nurses not to call elderly patients "darling" or "sweetie", and Age Concern points out that the older generation hate being called by their first names by people they don't know. There is also a practical problem by using what is believed to be a person's given name. A friend reports that an uncle, whose first name was John but who was always known by his middle name, Guy, was in so much pain in the late stages of lung cancer that he couldn't stop nurses asking "Are you all right, John?" This may not be the biggest thing facing a patient with cancer, but it's not what they need.

If we constantly relied on first names, we would forget the importance of surnames. So, scientists would have proclaimed last week they had located the Peter-Satyendra. These same scientists would have studied Albert's theory of relativity. Long pauses in plays would be referred to as "Haroldesque". It could get very confusing.

Yet perhaps we can forgive Diamond's over-familiarity. If you're trying to distance yourself from the Bollinger-swilling antics of the City, would you want to remind people of your surname, a word that conjures up Hollywood, bling and blood-soaked mines in Africa in one glittering, unbreakable stone? Or would you want to be known simply as Bob?