The Deputy PM has almost managed to keep his foot out of his mouth in Blair's absence. But not quite . . .
In Hollywood westerns deputies are sometimes sharp-shooting aces handed a badge along with a plea to help out in a crisis. But usually they are nincompoops, wide-eyed farm hands who fumble their pistols and make a hash of their knots. Which will John Prescott be this August?

This time of year is always John Prescott's opportunity for glory - when the Prime Minister and the rest of the Government take off for their summer break and the keys of Number 10 are handed over to the boy made good from Hull. It seems reasonable: August, after all, is the quietest time of the year, when most of the country is on vacation, too. The Deputy PM just needs to steer the ship of state through the calmest of waters. But for the Deputy PM, August always is a wicked month.

It's a chance for gaffes, as the past two summers have shown. Remember the time when he was snapped by photographers next to the Thames holding up a crab in a jam jar, calling it Peter as it slyly sidled into view? That was when he and Mr Mandelson locked their horns over who was running the country in the absence of Mr Blair.

Last year he took a deep breath, set up camp in the leader's office at Number 10, and tried to act the boss, but this too backfired. In seeking to give the impression of a man with a firm grasp on the affairs of state, he contrived only to suggest someone having an all-nighter while their parents were out. It wouldn't have been a surprise to learn he'd been flicking through his master's e-mail messages, rummaging through his bottom drawers, and trying on his football shirts.

Will this year be third time lucky for "Two Jags" Prescott? So far it's not looking good. On Monday, the Deputy PM slipped quietly into Number 10 where he has taken up residence in Tony's absence in the premier's own office. There are few other people around: chief spin meister Alastair Campbell is also sunning himself, as are the other top advisers. Not even Humphrey the cat is there to be kicked by a well-shod Prescott toe.

No wonder he got bored. His first venture out was to be photographed wearing a lifejacket, taking the wheel of a new RNLI lifeboat on the Thames. Being snapped in silly outfits is a Prescott speciality. Remember all the daft pictures of wetsuits? It's never a good move. This time was no different. Even a trainee spin-doctor could have predicted the result. Striving for that steady-as-she-goes, firm-hand-on-the-tiller look, he created exactly the opposite impression. The newspapers were not slow to present him as an edgy skipper, unsure which course to set and desperate to leap overboard. The Sun celebrated his tenure by portraying him as New Labour's hatchet-faced bulldog, recommending only that a neighbour change his water on Fridays.

Tuesday offered Mr Prescott a chance to be as serious as befits a statesman. Charles Kennedy had just been elected leader of the Liberal Democrats. Perhaps a moment for a little generosity of spirit? Mr Blair, after all, had taken time off from his Tuscany tennis lessons to offer his congratulations to the young Liberal blood.

But Mr Prescott's loathing of Liberal Democrats got the better of him in the end. Charles Kennedy began his leadership by pledging to become the voice of the poor because Labour is ignoring them. Prescott roared in retaliation on Radio 4's Today programme: "That's a bit of rubbish - a bit of rhetoric, I would imagine. The difference is, we're in government and we implement where they snap at our heels, if you like. If he wants to come on board with us, fine - but I think he'll find we're flying ahead of him on social justice."

Then he turned Rottweiler. Questioned on a Labour-dominated select committee's scathing attack of his transport department and on the question of rail safety, he barked: "I don't want to hear any more arguments about it."

Perhaps it was that encounter that persuaded him to lie low for a while. Or maybe it was all the warnings about not looking at the sun. But on eclipse day Prezza was nowhere to be seen. His master, no doubt, would have been there to lead the nation from Number 10's rose garden, with a pithy phrase about the people's eclipse.

On Thursday, the Deputy PM reappeared, this time on home ground. Not only was he at his hulking headquarters in Victoria (home of the unwieldy Department of Environment, Transport and the Regions) but he was there to talk about the sea. Mr Prescott famously left school at 15 and went to work as a steward on luxury liners. There he sat, flanked by the very ship-owners he once fought as an active merchant seaman trades unionist, listening and smiling broadly as they praised his scheme to give tax-breaks to shipping companies in return for pledges on training and expansion. P&O announced that the deal was so good that it would be repatriating its ships, nearly doubling the number of vessels that fly the British flag. It wasn't cheap. The tax break costs pounds 40m per year, a significant triumph in Prescott's ongoing battle with Gordon Brown's Treasury, which gave him the nod.

The announcement on the British fleet went down well with the unions and will win New Labour brownie points because of the shipping companies' praise. Mr Prescott also showed political acumen when his proposals provoked a furore among Scotland's dejected coastguards, who faced closures as part of this renewal of British shipping. He passed the buck to Lord Donaldson, the judge whose inquiry recommended the closures.

It didn't last. Verbal tangles are Prescott's trademark - he talks like a man trying to swat wasps out of his hair. He spoke excitedly about "the world's main financial centre here in Hull ... er, London." And he ended with a bungled attempt to be resonant. He knew, he concluded gravely, that today's announcements would be "a source of great proud to the seafarers". Back on Radio 4 - always a danger zone for the Deputy PM - he told the nation: "Many British sail ... err ... sailors are actually flying under flags of convenience ships because they do not have British Red Ensign flags ... err ... ships to sail on."

Being a deputy is always a hazardous assignment. On the few occasions you find yourself in charge, you also find yourself without a deputy. They are by definition whipping boys: they are obliged to affect powers they do not actually possess. And usually the boss doesn't want you to shine too much. Which must be why there are even whispers that the Blair camp would not actually mind if Prescott puts his foot in it again this year.