Alan Watkins: Yes, Mr Cameron is a Tory version of Mr Blair. He is a perfect, absolute blank

There has been nothing like it since they picked Baldwin in 1923

Fifteen years previously (some future historian of December 2005 might write), Margaret Thatcher had been ejected from Downing Street in tears. Much had happened to her party in the succeeding period, some of it good, most of it bad. The Conservatives had won one election; lost three; and given a flickering allegiance to no fewer than five leaders, of whom the latest was David Cameron.

Lady Thatcher herself saw her friends disappear by the year. Where had they all gone? What had happened to them? Lord Hanson, who had made a fortune through buying companies, breaking them up and selling off their constituent parts at bargain rates, was no more. Lord King, who had turned gross incivility into a form of corporate governance, had gone to a Better Place. Lord Archer, who had suffered a term of imprisonment, was deprived of the party whip in the House of Lords. One of her warmest admirers, the ageing roué Alan Clark, had died before his time.

True, Lords Parkinson and Tebbit would sometimes flit fugitive across the television screens to remind their audience of happier times. But the lady's greatest admirer was the Labour Prime Minister, Tony Blair.

As for Lady Thatcher, she led an increasingly reclusive life barricaded in that redoubt of the rich, Belgravia, where she was sequestered with her son Mark, who was himself denied admission to the United States following a scandal in southern Africa. Her daughter Carol, who was universally popular but to whom her mother had never been close (indeed, she had been brought up largely by a nextdoor neighbour), was buried in the Australian jungle in an attempt to make a name for herself on the programme I'm a Celebrity ... Get Me Out of Here!

Carol's mother would sometimes be led out by the arm, bent, pale, smaller than one remembered her, to attend memorial services at Westminster Abbey, St Paul's Cathedral or St Margaret's, Westminster, where she would be forced to listen to broken-backed renditions of "I Vow to Thee My Country" and other hymns favoured by dead Tories.

That's enough pastiche. There are no prizes for guessing the identity of the historian I had in mind. The point is that it has taken 15 years for the Conservative Party to get Lady Thatcher, and the terrible act of matricide which brought about her fall, out of its system.

All kinds of remedies were tried. Various pills and capsules were taken, to no avail. The patient was attached to tubes and needles. But the infection soon returned, often more severely. It took various forms.

Usually, as we know, it was about Europe. If currencies failed as the pretext for a party row, why, there were always constitutions. If these palled, borders, passports, drugs, policemen and immigrants were invariably a sound basis for a good quarrel. And if Europe failed, well, gay marriage, gay adoption, even gay clergymen could keep the Conservatives occupied for months.

Malcolm Muggeridge used to be fond of quoting, as an illustration of liberal fatuity, a sentence from a Manchester Guardian leader of the 1930s: "One is sometimes tempted to conclude that the Greeks do not want a stable government." Likewise, one was sometimes tempted to conclude that the Tories did not want to form a government of any sort ever again.

What has happened is not very different from what happened to the Labour Party from the mid-1980s onwards. As Neil Kinnock was the John the Baptist at that earlier time, so it was another Welshman, Michael Howard, who performed the same function for the Tories.

Mr Cameron has been accused of being light on policy. I can remember the time when the Labour Party was merrily tearing itself into small pieces over the bomb in 1959-63. In 1963-64 Harold Wilson carefully put together a policy which was subtly different from that of his predecessor, Hugh Gaitskell, and which kept the party more or less happy. In office, Wilson completely disregarded his policy. Not only did no one object: no one even noticed.

Similarly, in 1965-70 Edward Heath formulated a series of policies more detailed than any put forward by an opposition before or since. They were more free-market than corporatist. Indeed, if we are in the Baptist business, it was Heath rather than Enoch Powell who fulfilled that role in relation to Margaret Thatcher. But in government, Heath's measures were not only different: they were the direct opposite of what he had urged previously.

Heath was chosen in 1965 because he was thought to be another version of the immensely successful Wilson. "Abrasive" was the favourite adjective of that time. In the same way, Mr Cameron is thought to be another, perhaps more honourable, version of the even more successful Mr Blair. There is no point in pretending otherwise.

Why else is he being chosen? There has been nothing like it since the preferment of Stanley Baldwin at Lord Curzon's expense in 1923. Baldwin had at least been Financial Secretary to the Treasury and had played a leading part in the toppling of David Lloyd George in 1922. Mr Cameron, by contrast, is a perfect and absolute blank, even more so than Mr Kinnock was in 1983, or Mr Blair in 1994.

Leaders of the Opposition are not judged by their formulation of policy but by their performances at Prime Minister's Questions. Here we must be careful. Mr William Hague worried Mr Blair; made him uneasy. But it did him no good, availed him nothing, with the voters.

My own view is that Mr Hague's extra-terrestrial appearance, combined with the impression that Winston Churchill had been reincarnated somewhere in Yorkshire, was enough to scare off the citizens. For some reason, Mr Cameron's tempting of Mr Hague back on to the front bench as Shadow Foreign Secretary is being hailed as a great triumph for him. I am unable to see it myself.

But if an impressive performance at PMQs is no longer a guarantee of success in other respects, it does not follow from this that an unimpressive performance does not matter either. Mr Iain Duncan Smith could testify to the truth of that. And Heath's showing led his colleagues to ask regularly: Have we all made a terrible mistake?

Mr Cameron promises to go a different, more emollient way: partly because he thinks that is what the public wants and partly to discomfit Mr Blair and the benches behind him. I wonder how long that will last.