You have to go all the way back to 1913, when the factors that led to the outbreak of World War I were still in their ascendancy, to find Chelsea's first European player.

Nils Middelboe, a Danish international confusingly born in Sweden, was a defensive midfielder who had already been a star of two Olympic tournaments.

Standing at 6ft 2ins tall, he was inevitably dubbed The Great Dane; and in a decade-long career with Chelsea, punctuated by the 1914-18 conflict, he played 46 times, scoring once.

A banker by trade, he was said to not much like football, and refused to play away matches, due to commitments in The City.

By the time the Century was almost out Chelsea were fielding the club's, and the country's, first entirely foreign XI.

On Boxing Day 1999 at The Dell nine different nationalities kicked-off in blue, seven of those individuals now EU citizens.

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It is impossible to tell the story of Chelsea Football Club without looking at its European ties.

As of the end of the 2014-15 season, 69 players had been capped by a nation now a member of the EU (excluding the UK) while playing for Chelsea.

Those men have represented 14 of the 27 countries with whom we share the union.

With uncapped and youth team players, you can add another five EU nationalities.

Chelsea sixth most enduring servant, a man who made 494 appearances for the side, is Czech citizen Petr Cech.

Whether you think such a cosmopolitan turn of events has enriched the game, improving the club's chances; or unreasonably taken opportunities from homegrown youngsters – well, that may inform how you vote on Thursday.

Freedom of movement

Former football player Jean Marc Bosman
Key figure: Former football player Jean Marc Bosman

Amid much debate over who does and does not make our laws, there is one legal precedent which towers over football from an undoubtedly European angle.

Jean-Marc Bosman had an unremarkable career in the Belgian league, until the small matter of his contract became big news.

Union Royale Belge des Sociétés de Football Association ASBL v Jean-Marc Bosman (1995), better known as The Bosman Ruling, opened up freedom of movement for out-of-contract players across the whole of the European economic area.

Chelsea's first Bosman signing was Gus Poyet, from Real Zaragoza in summer 1997.

He went on to play 145 times, scoring 49 goals.

Chelsea's first free transfer: Gus Poyet is now a manager

But the most famous Bosman to arrive at Stamford Bridge was a titan of the European game, and unmistakably one of the greatest transfer coups in the club's history.

Michael Ballack was already a legend in Germany when he arrived in west London, and over four years in his new home he did nothing to tarnish that reputation.

'Der kleine Kaiser' played 167 times for Chelsea , scoring 26 times – none of which would have happened without that European ruling.

The greatest night in the history of Chelsea Football Club

Pinnacle: Petr Cech of Chelsea lifts up the UEFA Champions League trophy

When Chelsea won their first league title in 1955, they had an opportunity before them no other English champions had ever faced.

They were selected by French football magazine L'Equipe to represent England in the very first European Cup.

But it was not to be, as autocratic and xenophobic Football League secretary Alan Hardaker stepped in to ban the Blues from partaking in a competition he saw as an unwanted distraction from domestic football.

We will never know how Chelsea might have fared, as they were replaced by Polish side Gwardia Waszawa in the draw.

But Hibernian, of Edinburgh, made it through to the semis that season.

Real Madrid won the inaugural tournament, as well as the next four, and went down as one of the greatest sides in the history of the game – having not been tested against the English champions, who had every right to be there.

Top European Football Stadiums in pictures:

Fast-forward several decades, and the value of European competition is prized probably more highly in English football than anything else.

Qualification for it, via goals from a Frenchman (Marcel Desailly) and a Dane (Jesper Gronkjaer) back in 2003 is what first grabbed the attention of Chelsea's new Russian owner.

Many fans will have shared the joy, and occasionally the pain, of following Chelsea in Europe over the following years – and now that is (temporarily) not there, it is more keenly missed than ever.

Very few who were lucky enough to make it to Munich, on 19 May 2012, consider that date to be anything other than the greatest in their lifetime.

It was the day, unimpeded by petty English officialdom, Chelsea marched into Europe – with a side made up of nine different nationalities (five of them EU ), managed by an Italian, to became the Champions of Europe.

In Europe, of Europe, ruling Europe – and with a star on the shirt to just prove it.

With thanks to Paul Dutton and Rick Glanvill, whose 'Chelsea: The Complete Record' was invaluable in compiling this piece.

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