I'M NOT shocked by the news that at least seven prominent members of the Tory party smoked cannabis when they were at university. What is shocking is that anyone should be remotely interested in the fact.

"University student smokes cannabis" - as a boring headline it beats "Small earthquake in Chile: not many dead". There seems to be a fad for confessing peccadilloes. First it was Michael Portillo and his gay adolescence; then William "fourteen pints" Hague; and now the Cabinet members and the seven joints. Who cares? What next? "Home Secretary confesses he used to read The Dandy". "Chancellor of the Exchequer admits he ate two ice creams in one day".

It is said in all the papers that the public's mood is moving in the direction of legalising cannabis at just the same time that there is talk of banning cigarette smoking in public places. It looks as if the decision on what to ban and what to permit is extremely arbitrary and certainly out of all proportion to the risk involved.

Cannabis is called a "soft drug" - suggesting that it's harmless. As a matter of fact cannabis contains many more cancer-causing agents than ordinary fags. I don't say that's a reason to ban it. Why not let people choose for themselves? Whatever happened to the wise old maxim that said: "Everyone has the right to go to hell in his own way"?

I get dizzy with the pace of change in social mores. I'd just learnt that progressive Tories were against buggery and in favour of fox hunting when they switched those opinions round too. To cap it all there was a report in yesterday's paper which said that a leading academic recommends a 10p tax on fatty hamburgers to stop Britain's obesity levels reaching American proportions. What exactly is a "leading" academic anyway? What do they lead? What will they want to ban or tax next - pork sausages, dumplings, Yorkshire pud? Myself, I should prefer to see a ban on leading academics.

I confess to causing a disturbance at the new Tate Modern gallery, that re-ordered power station on the south bank of the Thames. It's at one end of the closed Millennium Bridge. At least when the bridge is re-opened members of the public will be able to walk from St Paul's Cathedral to the Tate in about five minutes - thus establishing a new shortest distance between the sublime and the ridiculous.

What the Tate needs is a visit from the little boy in Hans Andersen's fairy tale who alone had the courage to announce that the king had no clothes on. In the absence of this little boy I tried to do his job for him. Room after room of pretentious junk - quite literally in some cases. There is for instance what's called an "installation" in the form of an untidy workshop. It looks just like the mess that the builders have left at the back end of our church these last six months. This was where I caused my little bit of havoc. I ignored the pile of junk and drew the attendant's attention to the fire door. "Look", I said, "at that magnificent installation of a fire door!" "Oh no, Sir", replied the attendant, swiftly correcting my ignorance, "that's not a work of art; it's a real fire door". But I persisted: "How can you pretend that a piece of construction so beautiful and so finely-wrought is not a work of art?" I began to walk up and down, drawing other visitors' attention to the fire door. In the end the attendant called for his colleague and they had to restrain me. It was no use my telling them that what they called "making a nuisance of yourself, Sir" was really my own art work, my very own "installation". I had to leave, but not before I'd enjoyed my five minutes of "artistic freedom", my finger-pointing mockery.

*l Peter Mullen is Rector of St Michael's, Cornhill, in the City of London, and Chaplain to the Stock Exchange