The Sketch: Parliament's upwardly mobile get to grips with obstacles to progress

The niece of a countess sitting next to the son of a hereditary peer faced a baronet and an international banker's Oxbridge son educated at the third of Britain's four major public schools (and who defeated for the party leadership another old boy from his school, who himself had a double-barrelled name when I knew him at Oxford).

They were wrangling about how best to remove the "obstacles to progress" that children from poor households face. "You!" hecklers point and jeer. Alas, the obstacles tend to be the parents. Not reading to their toddlers, but leaving them in front of the television with a six-pack of full-strength. "With a few noble exceptions," Frank Field agreed with Clegg, "most children's life chances are determined by the age of five."

In an age when it's very hard not to be middle class, there is a state-created class of hereditary beneficiaries it seems impossible to improve. You may remember Frank's campaign against "neighbours from hell" in which he wanted to rehouse the diabolical in concrete hose-down cages under the motorway flyover.

He may have inconvenient opinions but at least you can see the deterrent effect. Will the Advocate for Access to Education send out messages of equal power and penetration? One of the few working-class MPs – or MPs with working-class origins – Hazel Blears in short, asked the Deputy Prime Minister whether he employed unpaid interns. Worse, there was his own start in public life. Intern to Harriet Harman. Or someone.

Clegg was happy to confirm that all Lib Dem interns are indeed properly remunerated "from today". As he was launching a campaign at 1.30pm to discourage this form of middle-class apprenticeship, it was a close-run thing.

But then, "don't do as I do, do as I say" is an honoured tradition in politics. Harman – a passionate proponent of equality – sent one of her children to a grammar school and the other to the Oratory. She confidently lambasted a remarkably resilient Clegg for trebling tuition fees. He then made an interesting assertion: "Every graduate will pay out less from their bank account for their student loans than under the present system."

Students of political promises may want to make a note of that.

Unintended effects are so rampant in this area that trebling fees may actually increase social mobility – by reducing the roll at private schools. Everyone's worse off but the indicators look better.

Clegg said his goal was a Britain where "what you know not who you know" determines how far you get on in life. It will set a brave new direction to 10,000 years of human history – but think of the odd fish you'll be sitting next to at work if that ever happens.

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