Foregoing the car to walk a few miles bathed in glorious Atlantic coast sunshine early last July, my wife and I finally secured a yearned-for opportunity to watch the start of the Tour de France.

The tour’s organisers and owners, Amaury Sport Organisation (ASO), claim it has the largest live audience (in excess of 5 million) of any sporting event on earth.

If the attendance 30km into last year’s opening stage was indicative, this figure was an underestimate.

I was certainly pleased we had left the car behind; the enormous crowds milling towards the D38, a minor road partially resurfaced for the tour’s opening stage, resembled those great waves of people one encounters before any major football or rugby match.

Everyone had come to enjoy the occasion; the racing felt secondary. Arriving as advised more than two hours before the peloton was due to career past our vantage point, we were soon being handed a cold beer, several wedges of differently-coloured cheese and a fresh baguette. This was not Anfield on a wet Tuesday November night.

Soon, the caravanne, a 20 kilometre procession of the tour’s sponsors, began its drive past. Manned mostly by attractive young girls, each strapped into almost 200 garishly-decorated sponsored vehicles to prevent them falling out, their job is to distribute 16 million branded gifts to the roadside crowds.

Almost thirty different brands and sponsors pay up to €5 million a year to have their goodies thrown into a forest of outraised hands.

Television crews precariously perched on the back of motorbikes whizzed by, negotiating speed bumps and the yelps of youngsters keen to be spotted by the cameras. The local gendarmerie needed only to raise a cursory arm to keep the crowds in check.

Once the tour’s participants had sped past (there were a handful of early leaders, so this took around ten minutes), everyone either retired to one of several nearby bars, or picked on some food while still perched at the roadside and listened to the live jazz band belting out a series of standard numbers.

Afterwards, a spokesman for one of the tour’s sponsors, told me that this is why they had invested several million euros in the event: “Look how many people came along here today. It’s fun and so we think it now makes commercial sense to be associated with Le Tour.”

The key word here is ‘now’. Up until five or six years ago, sponsors continued to give the Tour de France the widest possible berth.

It was a pariah, sport’s equivalent of damaged goods.

However much organisers protested to the contrary, amongst deep-pocketed, would-be commercial partners and sponsors the feeling existed that too many of Le Tour’s participants were fuelled, in part at least, by illegal substances.

And there was plenty of hard evidence to support those suspicions.

It meant that although it attracted tens of millions of television viewers and a colossal, loyal ‘live’ roadside audience, the Tour de France became, in sponsorship terms, the world’s cheapest high-profile sporting event with which to get involved.

It was even rumoured that several companies willing to inject cash into the tour did so on a deferred basis, paying their sponsorship rights fees only after the race had finished.

Few companies were prepared to make long-term commitments to the tour, while team sponsors insisted on escape clauses which enabled them to terminate contracts should the team be caught harbouring drug cheats.

No matter that sponsoring the tour was cheap; prospective commercial partners were more concerned that their brands would be tarnished by association with cheating.

That attitude was gradually changing after the tour’s organisers and teams, mindful of how much sponsorship money and TV rights fees they were effectively forfeiting, made an enormous effort to rid the sport of drugs.

Have they succeeded in making professional cycling completely drugs-free? Almost certainly not, but it is much, much tougher for cheats to inject with impunity.

Recognising this, sponsors have, over the past few years, shown an increasing willingness to get involved with Le Tour.

Last year, the tour’s four principle sponsors paid an average of €4.8 million apiece for the privilege, while a further 24 commercial partners injected between €1.1 million and €2.3 million each to acquire exclusive rights to use the tour’s logo and map on their communications and promotional literature.

Broadcast rights, secured by a €120 million deal between ASO and France Televisions signed in 2008 (which includes several other ASO cycling events and the Dakar rally) has recently been extended to 2015.

Team budgets are understood to have risen from €8.6 million to almost €10 million in the space of a couple of years; average team salaries are now pushing €200,000.

At long last, it seemed the Tour de France was, commercially-speaking, heading in the right direction.

Until on Monday afternoon when it was announced that Alberto Contador, winner of the 2010 race, will play no part in this year’s tour after the Court of Arbitration for Sport gave him a two-year ban after he tested positive for using the banned drug clenbuterol.

The 2010 Tour is the second to be decided through the courts in five years; the 2006 race winner Floyd Landis was also stripped of his victory following a positive test for testosterone.

Everything was supposed to have changed after Landis. Contador was cycling’s new golden boy, a handsome, polite, multi-lingual Spaniard set to be the sport’s face for several years to come, a figurehead capable of ensuring the sport received the financial rewards its audience and support justified.

Now, the commercial progress made since 2006 could grind to a standstill.

On Monday night, I called the same sponsor’s spokesman I previously saw on the Vendee and at a time-trial in Les Essarts, a small town which attracted almost 250,000 people on the tour’s second day last year.

“It’s bad news,” he said of the Contador verdict. “We would love to stay involved (with the tour), but it looks unlikely beyond our current agreement.”

Regrettably, for cycling and its millions of followers, the probability is such sentiment is echoed amongst many Tour de France sponsors.