Last week, to improve myself, I went to a talk at the Ashmolean. I’d never been to a museum talk before but thought I’d give it a go. Its subject was a view of Oxford High Street, painted by JMW Turner in 1810.

The museum has just acquired the painting with the help of about 800 public donations. Public appeals have been common since the National Art Collections Fund stumped up for a Holbein painting in 1909. But what was it about this painting by Turner that made it worth keeping hold of?

Anyone who happened to be free at the time of the talk could walk in, take a seat and find out. But not everyone did. I counted 52 other people in the room, all mind-bogglingly posh.

So as the speaker began his talk I started to think less about Turner’s painting and more about how to behave myself in front of my social superiors.

I had a rough idea of how to act. There are certain no-nos.

Obviously it would be inappropriate to sling my shoes up on the seat in front of me, crack open a can of Stella and shout. It would be wrong to offer around the packet of cashew nuts in my briefcase. But there are a couple of tricks I have yet to learn.

First of all there is the art of turning around to your neighbour and providing an ongoing commentary. The bespectacled mother and daughter in the row in front of me were very good at this indeed. Regardless of what the expert speaker had to say about Turner, they had something more important to add.

Next up it’s the delightful habit of nodding whenever the speaker says anything clever.

What the nod says is “you’ve dedicated months of your life to studying this painting – but I knew that all already.”

It’s the same I-Knew-That-All-Along nod that quiz show contestants give when they hear the answer to a question they’ve just got hopelessly wrong. The third and most magnificent habit of course, is the art of laughing at jokes that are not funny.

These gestures, through which certain people like todemonstrate how clever they are, fall on deaf ears in front of Turner’s painting.

Commissioned by an Oxford shopkeeper it shows the same view as you’d get if you boarded the number 5 bus outside The Queen’s College today, and stared out of the back window. It’s worth keeping hold of because it’s a bit of our history by Britain’s most famous artist. It’s nice to look at.

And there’s bad news for any snobs out there. It doesn’t matter how loudly you laugh, how violently you nod or how many more books you have read.

We are all looking at exactly the same painting.