He had a good boom, but an even better bust. He has been to the mountain. He has dined with kings, been offered wings, and once or twice he flew too close to the sun. Then last week, his credibility took a hammering. And what did David McWilliams do? Just like one of those debt thingys that were at the heart of the sub-prime crisis, he repackaged himself and moved along to another institution. The people's pop economist became a comedian.

The last decade wouldn't have been the same without McWilliams guiding us through the maze of finance, sociology, popular culture and Breakfast Roll Man. He brought economics to the masses, humour to a staid science, and the sons and daughters of the diaspora to Farmleigh. But just when his foppy haired, amiable presence was drifting towards national institution status, he goes and spoils it all by saying something stupid like, "It was me wot saved the country and Brian Lenihan from himself".

McWilliams' new book, Follow The Money, tells all about a private late-night visit to his home by Brian Lenihan, who was canvassing advice at the height of the banking crisis in September last year.

"The phone had rung about an hour before, so I was expecting him. Even so, as we'd never had a politician in our house, never mind a minister for finance, seeing the bulk of Brian Lenihan at the door came as a surprise," he wrote.

The visit was private, and even by his own account, McWilliams had pledged to keep it that way. He told Lenihan: "I won't tell anybody if you don't," but should have added, "until I have a book to flog."

Repel scorpions

The revelation, extracted in the Irish Independent, also contained the damaging allegation that Lenihan confided in Dave that he had little confidence in his departmental officials. Whether or not the allegation is accurate, it did Lenihan no favours.

Then there was the revelation that, on the night in question, Lenihan chewed cloves of garlic. But McWilliams neglected to mention that in ancient Rome garlic was used to repel scorpions.

Lenihan vehemently disputed much about the version, including that he had made any comment about officials.

The reaction has not been good. Marian Finucane suggested the apparent betrayal of confidence was "mean". Economist Jim Power described it as "despicable". By any standards it was below the belt. The stock of politicians is at an all-time low, but that does not give free rein to treat them as if they were something that the cat dragged in.

To a great extent, McWilliams is a victim of his own success. His decision to plumb the depths must have been informed by that great pal of right-on economists – the market. Currently, the book market in serious issues is top heavy. A whole range of books is on offer analysing how we arrived at this desolate juncture after a decade of partying.

The appetite for such weighty tomes can in part be ascribed to the publishing phenomenon that was The Pope's Children. This was McWilliams' 2005 pop economics/sociology tome that brought us Decklanders and Breakfast Roll Man and lots of cute stuff that distilled for easy consumption his interpretation of the essence of the Celtic Tiger. It sold over 100,000 copies and spawned the TV series In Search of The Pope's Children, which made for fine light entertainment.

The success of The Pope's Children awoke publishers to a new market. Now with it flooded, McWilliams had to come up with something original to sell his new tome. So he reveals all about Lenihan, and throws in something about Miriam O'Callaghan being the seductress of Montrose who deflowers petrified males in her boudoir of the Prime Time studio. Short of parading down O'Connell Street in the nip with the book held aloft, it's difficult to fathom what lower depths he could have plumbed.

On Thusday, he apologised, but McWilliams is a pro. The suspicion is that damage limitation rather than contrition was behind his backtrack.

Of course, Lenihan made a mistake. He thought McWilliams was offering advice on economics, when he should have used the occasion to seek guidance on communication. McWilliams' forté is communication. He is, as one of his fellow pundits might put it, a good economist, not a great economist.

For the last 18 months, he has dined out on being the principal soothsayer who had long forecast the bursting of the bubble. And he had. He first predicted that it would all end in tears at a conference in Ennis on 31 October 1998. The economy would crash "within a year or two", he said. "We are in real danger of moving from Celtic Tiger to Celtic Ostrich in a few short years," he said. He pointed in particular to the vulnerability of the housing market.

As it was, he was correct, just as you would be correct to note that one day a toddler will grow old and die. If potential housebuyers had heeded his advice then, they would be in an even worse situation now, as prices are back at 2003-2004 levels, not those of 1998.

Last week, he suggested that Bertie Ahern's exhortation in 2007 to "doomsayers" to commit suicide was directed at him. In fact, Ahern spoke out soon after economists like Alan Ahearne and Morgan Kelly had given their analysis of the impending doom. By then, Dave had been crying wolf for nearly a decade, but this time the beast was en route.

To be fair to him, the hot air has been accompanied by breaths of fresh air. His forthright manner in decrying the banks during the bubble was a refreshing antidote to the propaganda being peddled by bank economists. And he did voice his belief that the banks were going to go wallop in the weeks before they nearly did go wallop. That insight, and particularly his forceful manner of articulating it, was what prompted Lenihan to agree to meet him. McWilliams also has shown an ability for lateral thinking, floating ideas that are sometimes considered left field by the orthodoxy.

However, too many attempts at floating will inevitably lead to a sinking. Lately, he has been pushing hard for Ireland to leave the euro as a way of dealing with our competitiveness problem. The notion has been dismissed as ludicrous by voices from across the political and economic spectrum. As one economist noted: "We might solve our competitiveness problem but at the cost of destroying the economy."

Notably, McWilliams doesn't contribute to the highly rated Irisheconomy.ie blog, where most of the country's leading boffins share ideas and insights. It operates far from the headlines and TV cameras, out there where no self-respecting self-publicist should ever be found.

Pop economics

On the communications side of things, he is superb. He has to be credited for bringing his brand of pop economics to the masses. This he does through clever labelling and placing most economic conundrums within a digestible narrative. Sometimes, the narrative itself is more important than the story it seeks to tell. For instance, The Pope's Children, stuffed with bog roll man and decklanders and what have you, is a terrific snapshot of various categories of Celtic cubs. Except fleshing them out was a serious problem in the TV series when he couldn't produce any real examples.

In his other book, The Generation Game, the notion of calling home the sons and daughters of the diaspora provided another striking narrative, even if the practicalities of doing so are out there somewhere between Lilliput and Tír Na nÓg.

McWilliams is a first-class TV presenter, well-scrubbed, articulate and capable of investing passion in his, and his guests', every utterance. In his recent Addicted To Money programme, he traversed the world chasing a fix, looking up at the sky, as if expecting the apparition at Knock to come dropping at any minute.

In addition to brimming with ideas, he also possesses an uncanny ability to think like other great minds.

On 18 October last, he wrote an engaging column about his old classmates in Blackrock College and how the "smart" ones who had been in the professions got into property in 2005, having seen that the "stupid" ones were raking it in. The "smart" fellas' ignorance of dealing with risk then contributed to the collapse.

By coincidence, five days earlier in the New York Times, journalist Calvin Trillin wrote a similar column about classmates in a US college. Truly, McWilliams is a man without borders, communing on a psychic level with his fellows across the globe.

One of his ideas led to the Irish Global Economic Forum in Farmleigh House last month, which called home the diaspora and a few tax exiles. Many ideas were exchanged, and we await any positive result.

Player on a Prayer

As it was McWilliams' baby, he was in attendance, and was one of the few to actually claim a fee – €10,000 – from the Sean-Bhean Bhocht, in whose name they had gathered.

He contacted Micheál Martin with that suggestion, and if Lenihan is to be believed, he is, or was, prone to contacting other ministers with his views. Despite his protests, he would appear to enjoy the notion of being a player.

The failure of the government to properly acknowledge his contribution rankles. Asked prior to his latest TV series whether he would interview Brian Cowen, he replied: "You must be joking. You must realise that the top brass in Fianna Fáil knows nothing. They knew less than the average bus driver. Fianna Fáil is a family business. Cowen and Lenihan, their dads were politicians."

One wonders whether such an analysis was informed by the appointment of Alan Ahearne rather than himself as adviser to Lenihan at a time of such turbulence.

His own assessment of his status as a player was obvious in the tone of his account of Lenihan's visit. McWilliams' intervention ensured that Lenihan acted correctly. The great unwashed now know how vital he is to our survival.

Having saved the country, he has now moved on to save The Panel. He debuted on Thursday as the new host of the comedy show, and there is little doubt that he will be a huge success in that role.

Breakfast Roll Man has become breakfast dole man. McWilliams' latest book includes more colourful characters like Fin Boys, who are apparently lads in sales with fancy hair. If he himself was a character in one of his narratives he would have to be The Player On A Prayer. Since the unseemly filleting of Lenihan, he may require a wing to accompany the prayer in order to maintain his credibility as a leading noise in the public square.