As expected, the Government announced yesterday that it will overrule its own advisers and reclassify cannabis as a Class B substance. This will “send out a message” that the drug can be dangerous. As I'm sure the criminal law is not the way to do this, why does something in me raise a quiet cheer? It's not as if the Government's right. This diary inveighs ceaselessly against the “sending out a message” school of lawmaking. The Government had asked its Advisory Council on the Misuse of Drugs, experts in their field, a clear question; and they had given a clear answer.

Reclassification was unwise. Ministers are unwise now to propose it. But what I cheer is this: that the Cabinet has taken its own decision after hearing, but refusing to rubber-stamp, the recommendations of an unelected body.

Advisers advise. Ministers decide. This is how it should be. A tendency has grown (perhaps in line with our diminishing respect for politicians) for governments to farm out tough decisions to bodies of experts, lawyers or retired judges - abdicating to “the science”, the judges or the professionals, a politician's democratic responsibility to make the final choice.

When last year a committee of experts recommended Manchester rather than Blackpool for the (now abandoned) supercasino, I longed to see the Secretary of State, Tessa Jowell, stand up in the Commons and say she'd received the advice but chose Blackpool anyway, because she thought her experts were wrong.

So those like me who have no doubt that cannabis should stay in Class C can console ourselves at least with this: that the present Cabinet will never again be able to duck behind a panel of advisers when challenged on an unpopular decision. If they can overrule this most impressive of advisory councils, they can overrule any others.

The whole world appears to be telling Gordon Brown how to rescue his prime-ministership, and this columnist has tried his readers' patience already with the oft-repeated cry that Mr Brown is sunk.

Panic is rational. But on the basis that all is probably lost anyway, there's one panic measure Brown might try. He could reshuffle himself.

For all our doubts about this man, we do still suspect he has a grip on figures and relishes hard work. And we're worried about the economic future. So why not announce that the Prime Minister has decided to make his honorific and historic title, “First Lord of the Treasury”, a reality, and gather the Chancellor of the Exchequer's portfolio under his own wing, releasing Alistair Darling for other duties?

“While Britain faces the world economic slowdown,” Brown would say, “I shall take charge of the Treasury. I have a first-class Cabinet whom as Prime Minister I'll oversee. Meanwhile, in these exceptional circumstances, I shall focus on bringing Britain through the economic storm.”

It wouldn't make any difference, of course. But in presentational terms it might help.

How times change. Two weeks ago we heard that one of the Tories' leading donors had been flying to Monte Carlo for sex parties with four prostitutes, one gigolo and a trilingual bisexual. There had been something in the News of the World, and in other papers the story surfaced ten days ago, so I expected quite a fuss last week. But the story just fizzled out. We can't get excited about it.

My mind goes back only 12 years to when a little-known Conservative backbencher endured weeks of sensational coverage over the question of whether he and a male friend had known, when booking a room for two in France for a night, that it would have a double bed.

Then, of course, the Tories were deeply unpopular. So is that the difference today, or have sexual attitudes changed? And does a trilingual bisexual have three languages or (more usefully) three tongues?

Online (it's free, at earthobservatory.nasa.gov/Newsroom/NewImages, in Nasa's Earth-from-space continually updated photo gallery), I've been watching the swollen Apodi and Piranhas rivers in northeastern Brazil dumping silt into the Atlantic, and vast tails of swirling sediment in the Gulf of Alaska. In the Amazon tributaries I've seen millions of tons of soil gouged from thousands of miles of riverbanks.

Soil erosion will be raising sea levels as surely as melting ice. Movements in the Earth's crust will raise (or lower) sea levels too. Are all these reliably calculable? How do they mesh with global warming to produce the overall picture?

I pester scientist friends to tell me, but they reply boredly that doubtless someone will have done the calculations, but they cannot say who.

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