To celebrate the 50th anniversary of Norman Mailer's above-average piece of journalism, and because the Deputy Prime Minister's company, on day two of our fortnight together, was beginning to jar, and because I could think of nothing better to do, I took Cleggy to Asda. “Nick" is no Superman and Mailer didn't bang out 20,000 words on JFK stalking the aisles at an out-of-town Walmart, but in these dog days of August it's any excuse for a trip out.

Clegg performed exactly as you would expect him to when confronted by live shoppers - competent but unexciting. Certainly he had done his research and was up to speed on the price of milk and the bewildering array of special offers ("Buy one chicken, get one free!" - this is in the meals-for-one section) but he lacked flair. It was sadly noticeable that many of the shoppers with whom he attempted to strike up an acquaintance were reaching for their mobile phones early into the forced conversations. Between us, when it comes to the paying public, Cleggy's a bit of a clinker.

Which makes him the perfect man to hold the fort. If you wrote a national newspaper column, he would be the obvious choice as holiday replacement: a columnist who does not entertain the reader but relentlessly and single-mindedly reminds them of what they are missing. If Cleggy weren't so damned sensitive, I would have placed a poster behind him at press conferences saying "Dave is away".

The DPM's lack of personality was one of the main reasons we offered him the job in the first place. Just as John Prescott's job was to make Tony Blair appear eloquent, so Nick's is to make Dave look electrifying.

It is, however, only a mask. And rereading Mailer's piece (in particular his account of the demonstration at the Democratic convention for the charismatic Adlai Stevenson rather than the slick JFK), I was reminded of the threat posed by the man who might be nominated for the leadership as Stevenson was by Eugene McCarthy: "There was only one man who said let's talk sense to the American [British] people. He said the promise of America [Britain] is the promise of greatness. This was his call to greatness . . . Do not forget this man . . ." Boris.

The mayor will not challenge Dave, Sam and Baby at this year's conference, but next year when things are sour and stale and not even the presence of Nick can make Dave seem exciting . . . We shall see.