“We met at Stamford Bridge. I took them into one of the Millennium Boxes and within about 15 minutes we'd done the deal.”

That’s how former Chelsea Chief Executive Trevor Birch recounted the seminal moment in 2003 when he took Roman Abramovich and his advisors into a room and agreed the outline of a deal to sell the club to its current owner.

It only took 15 minutes, but that may well have been the most important quarter of an hour in English football’s history. Within a year, Claudio Ranieri had been replaced with Champions League winning manager Jose Mourinho, and Chelsea were never to be the same club ever again.

When you look at the history of billionaires taking over English football clubs, Chelsea is the first in a long line, but even with their success over the last decade it is almost impossible to match that first season under Jose Mourinho.

In many ways, that is Mourinho’s most underrated achievement. From winning two European titles in two years with unfancied Porto in the unfashionable Portuguese league, to dethroning the fabled Barcelona of Pep Guardiola to win an unprecedented treble with Inter Milan, perhaps it’s not surprising that the Portuguese coach’s first season at Stamford Bridge is neglected when the laurel wreaths are being handed out.

He may have won the Premier League, and even the League Cup, but failure to progress past February in the FA Cup and losing out in the Champions League semi-final to a Luis Garcia ‘ghost goal’ perhaps mean that Mourinho’s first great Chelsea team go somewhat under the radar.

There are a few reasons for that. Just the previous year, Arsenal had gone the entire Premier League season unbeaten, and so the sight of Chelsea winning the league having started the campaign with a Champions League winning manager and seemingly infinite money was less than edifying. Perhaps some - in the Arsene Wenger mould - might have seen it as morally dubious. And given their inability to go unbeaten, well, money can’t buy you love.

The other reason it might not be held up as the Mourinho pinnacle is that Chelsea won the league once again the next year, but by then the coach had continued his squad overhaul.

It was a team which wasn’t yet built in Mourinho’s image, and comprising of players like Scott Parker, Jiri Jarosik and Alexey Smertin, all of whom left the club at the end of the season. That’s in fitting with Mourinho’s normal timetable.

The overhaul comes after the first season, and the second is when the masterstroke really happens: as a manager, he’s so good at identifying weaknesses - both in his own team and the opposition - but although the team he had in the second season is probably a better one than he had in the first triumph, the first title victory was better.

Not only did Chelsea win the league, but they did with the best defence the Premier League has ever seen, conceding just 15 goals and winning by a 12-point margin. They were almost unstoppable - certainly barely penetrable.

A settled side has always been a Mourinho hallmark. The accusation that he doesn’t know his best team will rarely be levelled at him, even if his tactical pragmatism sometimes leads to selection choices with the opposition rather than his own team in mind. That settled side saw five players make over 50 appearances for the club that season. One of them was, unsurprisingly, Claude Makelele, who carved out a new position which is now named after him.

That immovable defensive unit is why Mourinho’s first season in English football is in the record books having conceded 15 goals in 38 games, and it’s why it will be remembered, even if Arsenal’s victory the season before gets the glory of being invincible.

Arsenal fans have a song about that season, and the world knows the team as the Invincibles. They are revered and respected; they are legendary. But few remember that Mourinho’s Chelsea went so very close to the same feat. They lost only once.

It shows the price of one failure when the margins are that tight. One rainy day in Manchester, when Chelsea were felled by a Nicolas Anelka penalty and Mourinho lost his first game in English football to Stuart Pearce: that’s the only reason that 2004/05 Chelsea aren’t widely seen as the best team in the history of the Premier League with not only the best defence, but the invincible one.

That defeat, though, may just have been what they needed to achieve such high levels in Mourinho’s first season. In the next game they faced Blackburn Rovers and won 4-0.

In the nine games immediately after the defeat in Manchester, Chelsea scored four goals on six occasions. It was as if they knew the chance at immortality had departed and Chelsea blazed to whatever glory they could grasp in a whirlwind of fury at the injustice of the world.

It’s not that Chelsea don’t get the credit for a near-perfect season. Nor is it the case that Jose Mourinho and his initial Chelsea machine is overlooked in the Pantheon of the great teams of history.

But Manchester United’s 1999 treble-winning side and Arsenal’s Invincibles are often held to loftier heights, not because the teams were obviously better, but because their achievements are more symbolic, more seminal. Perhaps the greatest achievement of the Roman Abramovich era is the Champions League victory in 2012, one that eluded Mourinho at the club.

It shows how difficult an unbeaten season is. And it shows how difficult a treble is. Those feats are worshipped for a reason, and Chelsea - despite coming incredibly close to doing both - didn’t quite make it.

And it also shows that, whatever happens in football’s future, and however much is spent by clubs, there are still some things that may never be repeated - United’s treble, Arsenal’s Invincibles and Chelsea’s 15 goals conceded are feats which will likely never be repeated again. Or if they are, we’ll be witnessing a very special team indeed.

Chelsea’s original Premier League winning side deserves to be spoken of in the same vein as those other greats, and they should be considered Chelsea’s greatest side.

And even if Trevor Birch’s 15 minute meeting in 2003 changed the face of the Premier League forever, it was only a year later when his club’s defining season took place.

https://video.footballfancast.com/video-2015/PL25(04-05).mp4