They are billed as the Robin Hood club of Spanish football, the challengers to the old hegemony of Real Madrid and Barcelona. Now Atletico Madrid have a chance to strike at the heart of the new money in English football too, when they face Chelsea in the Champions League semi-finals, adding to the lustre of Diego Simeone’s team as the great outsiders.

You could say that all but the supporters of the three other clubs in the Champions League semi-finals feel an affinity with Atletico and a closer look at their tax affairs would tell you just how close that affinity runs. Since a seven-year court case in Spain finally reached a verdict in 2011, Atletico have begun paying back a jaw-dropping €171m (£141m) in unpaid taxes to the Spanish purse. By any standards it is a remarkable sum and it comes against the backdrop of the €41bn European Union bailout that has been extended to the Kingdom of Spain.

It is not just that the neutrals will be backing Atletico in the Champions League. Rather more than that, if you’re an EU taxpayer, you could even claim to have funded them, indirectly.

The story of Atletico is one of those troubling tales of God-awful governance and extreme liberties taken with the payment of taxes, in a country where youth unemployment alone now stands at 55 per cent. Were it not for the ability of Simeone to build a competitive team on a relative shoestring, just as Raddy Antic did with his double-winning Atletico side of 1996, the club’s capacity to pay tax debts – to survive – would be greatly reduced.

At the start of this season, the tax debt of Atletico stood at €167m, which fell to €125m by the end of last year. A further €30m is due before the end of the season, which may or may not have yet been paid. Even so, they are not expected to have cleared their tax debts until the end of 2018.

The Robin Hood of European football? That would be stretching it. No one could deny that there have been some bandits in charge at Atletico over the years but it is a far from glorious history.

A guide to the Champions League semi-finalists Show all 4 1 /4 A guide to the Champions League semi-finalists A guide to the Champions League semi-finalists REAL MADRID Best: Winners (1955, 1956, 1957, 1958, 1959, 1960, 1966, 1998, 2000, 2002)

Star man: Cristiano Ronaldo

Manager: Carlo Ancelotti – has won the league in England, France and Italy, as well as the Champions League twice with Milan, and is now expected to deliver ‘la decima’ – Real Madrid’s tenth European title

Top scorer: Cristiano Ronaldo (14)

Top assist: Karim Benzema/Angel Di Maria (both 5)

Overview: After sailing through the group stages unbeaten, and then dispatching Schalke 9-2 in the last 16, Real Madrid were the form team in the tournament until their scare against Dortmund. The 2-0 defeat in Germany, albeit without their talisman Ronaldo, has revealed a chink in the armour, but you still wouldn’t want to draw them. GETTY IMAGES A guide to the Champions League semi-finalists CHELSEA Best: Winners (2012)

Star man: Eden Hazard

Manager: Jose Mourinho – The ‘Special One’ is looking to become the first manager to win the competition with three different teams having succeeded at Porto and Inter

Top scorer: Samuel Eto’o/Demba Ba/Fernando Torres (all 3)

Top assist: Oscar (4)

Overview: Despite losing twice to unfancied Basel, Chelsea topped their group and saw off the tricky task of Galatasaray in the last 16. Needed a last minute goal to scrape past PSG in the quarter-final, and will go into the semi-finals as underdogs – as they did in 2012. PA A guide to the Champions League semi-finalists BAYERN MUNICH Best: Winners (1974, 1975, 1976, 2001, 2013)

Star man: Franck Ribery

Manager: Pep Guardiola – in his first season at Barcelona he won a treble that included the Champions League, and he’s on course to do the same in his first season at Bayern. If he does it his place among the greats will no longer be in doubt.

Top scorer: Thomas Muller (5)

Top assist: Arjen Robben/Phillip Lahm (both 3)

Overview: Aside from a defeat at home to Manchester City, by which stage qualification was already secured, Bayern have been almost perfect, blowing away Arsenal and Manchester United in the knock-out stages. Favourites to become the first team in the Champions League era to retain the title. A guide to the Champions League semi-finalists ATLETICO MADRID Best: Runners-up (1974)

Star man: Diego Costa

Manager: Diego Simeone – the only manager left who was at his club last season, Simeone has built a team performing beyond the resources of Atletico, with a real shot at a first Spanish title since 1996.

Top scorer: Diego Costa (7)

Top assist: Gabi (4)

Overview: Atletico are the only unbeaten team left in the competition, and having seen off Milan and Barcelona they deserve their place in the semi-finals. They may be the only team left never to have won a European title, but they can no longer be considered underdogs, and everyone will want to avoid them. EPA

The worst of Atletico’s history dates back to the change in Spanish law in 1992 that dictated all but four clubs – Real Madrid, Barcelona, Athletic Bilbao and Osasuna – had to convert into plcs. The Independent revealed in August that this law is the subject of a European Commission state aid investigation, which could well force Real and Barcelona to give up their advantageous membership-based models.

In 1992, Atletico were owned by Jesus Gil and the club required €13m (in today’s currency), a significant sum then, mostly because of the debts run up by their owner. Gil did indeed put money into the club, but only long enough to gain control of the shares. A Spanish court found almost 12 years later that, having deposited it to gain control, he removed it within a few hours.

Over the following years, the Spanish establishment gave Gil much leeway and only came knocking when his political party looked like it could be a threat (Gil was a mayor of Marbella in his time, and publicised the resort city on Atletico’s shirts).

In the meantime there was the league and cup double under Antic and the signings of Christian Vieri and Juninho the following summer, although the Italian was sold to Lazio after only a year. By 1999, the club was placed in the Spanish equivalent of administration, with the Guardia Civil encircling the Vicente Calderon Stadium in their patrol cars on the morning of the ruling. In 2000, Atletico were relegated.

Gil was reinstated as club president but died in May 2004, shortly before the courts finally ruled on the club’s tax affairs from 1992 to 1999, a period which included the conversion to a plc. The judgment described that conversion as a “fraud” and suggested that the club was being used for money-laundering, not least in the signing of five African players for €15m who all conspicuously failed to make the grade.

Since 2004, the club has fought a long, debilitating battle against its tax liabilities in the courts, which only reached their first judgment in 2011, arriving at a final figure a year later of €171m. Now, more than 20 years on since their conversion to a plc, Atletico are finally facing their responsibilities and paying the tax they owe, albeit in a very different economic landscape in Spain to the one when all this began.

They are, without a doubt one of the worst-run European clubs of modern times, and testament to the old wisdom that when the politicians and accountants have done their worst, it is the ingenious football men like Simeone who save a club. They were burdened with Gil before the plc conversion (his son Miguel is still involved) although that iniquitous ruling undoubtedly made things worse.

As for the process Real and Barcelona were exempt from, it can only be hoped that the European Commission’s competitions’ commission finally takes action and levels the playing field in Spanish football. One of the advantages of their non-plc sports club status is that Barcelona can pursue Joan Laporta, their former president, personally for the €47m losses he allegedly racked up in his time. As a plc, there is no recourse for Atletico to do the same.

Can Atletico maintain their position fighting the duopoly of Spanish football? Their annual revenue is €120m compared with the €500m of Real and Barcelona. They earn just €50m from television, less than a third of the big two. They will struggle to escape the fate that engulfed the likes of Deportivo La Coruña, Valencia and Villarreal, who have all briefly challenged but then fell away. And that is before we examine the issue of third-party ownership as it relates to so many of Atletico’s players.

Given the shocking manner in which Atletico have sought to avoid their tax liabilities, right up until the last few years, it is hard to see them as the glorious rebels of Spanish football. Their recent success has had most to do with the talent of their Argentinian manager and not forgetting Quique Flores, who won the 2010 Europa League. But for most of their modern recent history, they fought as dirty as anyone, and are only now paying their dues.

Keane’s cutting criticism of Wenger’s Arsenal is merited

Roy Keane once said as a player that he resented the ceremony of trophy presentations so much that he would rather the team were given them in the dressing room, so his verdict on Arsenal’s reaction to their FA Cup semi-final penalty shoot-out victory was hardly a surprise. “These Arsenal players need a reality check,” he said on ITV. “They’re celebrating beating a Championship team.

“We saw last year when they got in the top four, they celebrated at Newcastle,” he went on. “We’re talking about Arsenal football club here. It’s about winning trophies.” Put it this way, you would never have caught Keane taking a selfie on the pitch (unlike Santi Cazorla and Aaron Ramsey).