VINCE was only missing his headmaster's robe as he addressed the school assembly and tore a strip, yet again, off those naughty Conservative schoolboys Cameron Major and Osborne Minor.

Last year, his Lib Dem colleagues rolled their eyes and despaired at how the Business Secretary launched into the likes of the Bullingdon Tories. Now, with just seven months to go before the General Election, everyone is doing it.

At one point, headmaster Cable singled out the Chancellor with a scowl and suggested his pants were on fire as he told members of the "yellow peril": "Any politician who tells you that the next government can balance the budget and avoid tax increases is lying to you."

A speech from the good doctor is always an enjoyable exercise in target practice such as: "The Tories are reinventing themselves as Ukip but without the beer while the Labour Party is offering us French Socialism but without the sex."

Up first for the Cable cane was the amnesiac Labour leader. Referring to Gladstone, a fine Scottish MP (from Liverpool), the SoS remarked how his feats of oratory were legendary.

"Not least," explained Vince, "was his speech on the Bulgarian atrocities. He is said to have spoken for five and a half hours, without notes, from memory. As far as we know, he didn't have to issue a statement the following day apologising for forgetting to mention Bulgaria or the atrocities."

He referred to the Tory leader's own Mr Memory exercise, delivering a 45-minute speech on "hoodies and huskies" without notes.

"Which raises an interesting question," mused Master Cable to his class. "Is it worse for politicians to forget what to say or to remember what to say but forget to do anything about it?" Clever stuff.

The final target for punishment was naturally enough the swivel-eyed right wing elitists and their contradictory, counter-productive view on foreign workers.

"The Tories for their part," explained the cabinet minister, "are horribly torn between open economic liberalism and their inward looking, Ukip facing grassroots, who probably see Clacton-on-Sea as the new Constantinople, holding out against the alien hordes."

We train Chinese engineers, he argued, but then insist they go home just when British industry needs them. "But, of course," bemoaned the head, "there is always a warm welcome isn't there for dodgy billionaires".