Howard Jacobson: When did we stop seeing modesty as a virtue?

If there’s one thing a parvenu has to do – otherwise what’s he risen from nowhere to somewhere for? – it’s boast

Cruddas – Cruddas, for God's sake! Could Dickens himself have come up with a better name for a Hackney-born self-made billionaire braggart bagman? "You knows my wicious ways," said Charlie Cruddas, tapping his nose with a finger that bore the marks of being in every pie in Brownnose Alley. "Now all you needs to know is my price. 'Igh, Mr Buzzard, wery 'igh indeed. 'Cos I 'as influence, I 'as."

A bit fat, that style of writing, for our lean times. Here's why we should be thankful for the Conservative Party: whatever our squeamishness in the matter of caricature, we can always rely on Tories to caricature themselves. They actually do take money from the poor to line the pockets of the rich; they actually do gallop through the centre of Chipping Norton on horses lent by friends any wise man would run a mile from; they actually do punish pensioners improvident enough not to have something stashed away in Bermuda or Liechenstein; they actually do think it behoves them to inhibit the drinking of the working classes (that's when they're not too drunk themselves to think anything) and they actually do (or did) employ as party treasurer a "Monaco boy" with an Essex accent by the name of Cruddas.

Though we castigate the Tory party for being a place where old Etonians can nod off in one another's company, in fact it's their hankering for the common touch that gets them into trouble. Was there not something embarrassingly costermonger about the Chancellor's slogan that the country was "open for business"? Touch and go, was it, between that and "open all hours"? As for the rumour that Osborne wanted to hang a sign from the front door of No 11 saying "Lovely to look at/ Delightful to hold/ But if you should break me/ Consider me sold", I can neither confirm nor deny it.

Then, just days after a budget so transparently unjust that Ed Miliband had only to run his hand through his hair to win the debate, along came "Mother" Theresa May showing she was au fait with "preloading" – that ancient proletarian ritual, still prevalent in the most deprived areas of the country, of getting pissed at home before you go out to get pissed on the street. An insider knowledge of the ways of ordinary folk that was on display again when the Tories suggested they hoard Cornish pasties – Cameron's takeaway of choice – in jerrycans stored in their groundsmen's sheds.

But with Cruddas we encounter a quality which, in fairness to its traditions, we don't normally associate with Conservatism at all. Boasting. If there's one thing a gentleman knows he has no need to do, it's boast. And if there's one thing a parvenu has to do – otherwise what's he risen from nowhere to somewhere for? – it's boast. Of the fools, animal or human, who enliven the pages of Aesop, the most common is the boaster. "Pretend this is Rhodes and jump then," say bystanders when a traveller boasts that in Rhodes he had jumped further than anyone had ever seen. Of the fools we encounter in the fables of our own lives the boaster is the easiest to confute. "Jump, then," we say, and there's an end of it. If Cruddas's boast, that a few shillings could buy you the Prime Minister's ear, wasn't empty, it's a serious matter for the Tory party. But if it was all bluster, how did he suppose he would not be rumbled?

That's a question we are forced to ask just about every time we turn on our television sets and hear competitors on some reality show or other singing their own praises. I long ago decided The Apprentice was not for adults on account of the inane boasting at its heart; not just the boasting implicit in the replete self-satisfaction of its host (if you've done so well, how come you're reduced to this, Lord Sugar?), but the feeble bragging of the contestants whose self-proclaimed marketing genius is given the lie three minutes into programme one when they can't give away an umbrella in the rain.

Yes, these are self-selecting shows; you have to be a dickhead to go on, so it stands to reason you'll say dickheaded things. But the culture of idiotic boasting is now so widespread that it must originate with the producers of these programmes, desperate to confer grandeur on what's vapid, to suggest drama where there is none, to make heroes of buffoons and, of course, when it comes to talent shows, to make buffoons of sad sacks.

Take a look at what they've done to Four Rooms, a sort of competitive Antiques Roadshow, in which sellers choose between rival bids from dealers said to be "masters of the dark arts of valuation". It had a laconic charm first time round, but it's returned as another excuse for gross posturing, with the dealers compelled to pose like The Avengers, vamping and camping and pluming and snorting and otherwise trying to look dangerous, telling us how they never fail to get what they want and then failing to get it at the first opportunity.

Almost everything that now happens on British television is crass, by turns timid and indecorous, but the boasting mania is the last scrape of the barrel. Modesty was once a virtue. Bring it back says I, or I will do such things – what they are yet, I know not; but they shall be the terrors of the earth.