James Milner reacts as City were dumped out of the Champions League by Barcelona

Manchester City, Arsenal and Chelsea all dropped out of the Champions League at the last 16 stage, leaving Everton to battle it out in Europe alone.

But will Premier League side's failures have an impact on the fourth Champions League spot? Here, we explain the murky world of coefficients...

Will the Premier League always get four Champions League places?

No. That coveted fourth place in the Premier League – occupied by Arsenal for three of the last four years – has been a privilege since the 2001/02 season.

For fairness, UEFA hand out Champions League places depending on how a particular country has performed in the last five years. At its height, the Premier League had eight Champions League finalists in eight seasons between 2005 and 2012, winning three. But events of the last two-and-a-half years have threatened to ruin all that hard work…

Why are people now saying the Premier League could soon lose a Champions League spot?

Chelsea were knocked out of the Champions League by PSG last Wednesday

English clubs' underwhelming record in Europe this season was highlighted yet again this week when Arsenal and Manchester City were both knocked out of the Champions League at the last 16 stage, along with Chelsea the week before.

Liverpool went out at the group stage and were then knocked out of the Europa League round of 32 along with Tottenham, Hull failed to reach the group stages of the Europa League, and Everton are the only side left in Europe’s secondary competition.

Which countries get which places?

Currently, the top three ranked countries – Spain, England and Germany - are given four Champions League places, while the three countries below - currently Italy, Portugal and France - are given three.

The countries are ranked on a coefficient score, based on 'points' gained from performance in the Champions League and Europa League.

How is this coefficient score calculated?

Santi Cazorla of Arsenal looks dejected as Monaco players celebrate progressing

The coefficient is calculated by working out an average score for the country, which is gained by dividing the number of 'points' obtained by the total number of clubs representing a country (for example, England have seven clubs this season).

That resulting number is then added to the results of the previous four seasons to calculate the coefficient.

How do you gain 'points'?

Still with us? Good. Each team gets two points for a win and one point for a draw, though points are halved for matches in the qualifying and play-off rounds.

Clubs that reach the last 16, quarter-final, semi-final or final of the Champions League, or the quarter-final, semi-final or final of the Europa League, are awarded an extra point for each round.

In addition, four points are awarded for participation in the group stage of the Champions League and four points for qualifying for the last 16.

So how many points have we got this season?

Manchester United reached the 2011 Champions League final, losing out to Barcelona

Arsenal have gained 21.5 points, Chelsea 21, Man City 15, Everton 14, Liverpool 10, Tottenham 11 and Hull 2.5, meaning up to now England have scored 95 points. Dividing that by seven gets you 13.571, England’s current coefficient score for the season.

How does this compare to other countries this season?

England’s score of 13.571 is currently fourth-best; Spain have 15.785, Germany 14.428 and Italy 15.

So where are England in the overall rankings when taking into account the past five seasons (including 2014/15)?

England are currently second in the overall coefficient ranking – the one that counts - with 80.391 points over the past five seasons. That's 18.357 (2010/11) + 15.250 (2011/12) + 16.428 (2012/13) + 16.785 (2013/14) + this year's 13.571.

Spain are top with 95.57, while Germany are just behind England with 77.986.

Could anybody overtake England this year?

It is virtually impossible for England’s closest challengers, Italy, to overtake this year. They are currently 14 points behind England in the overall standings. To put that into context, in the whole of the 2013/14 season, Italy gained 14.166 points, while England gained 16.785.

However, with the 2010/11 season dropping off the coefficient list next season, the gap will narrow considerably. With Manchester United reaching the final in 2011, England gained 18.357 points to Italy’s 11.571, meaning Italy will gain just under seven points.

The most points scored in a single season in the past five years was Spain's 23 in 2013/14 when both Atletico Madrid and Real Madrid reached the Champions League final, as well as Sevilla beating Benfica in the Europa League final.

So Italy are the biggest threat to the Premier League's fourth spot?

Everton are now the Premier League's only hope in Europe

Yes – and they still have six teams playing this season. Juventus are into the Champions League quarter-finals, while Torino, Roma, Fiorentina, Napoli and Inter Milan remain in the Europa League.

However, it would take a few years of rapid decline for Italy to overtake England in the coefficients.

What can Everton do to help the situation?

A Champions League or Europa League win usually gains a country around five points (depending on qualifying-round participation) towards that season’s overall coefficient, so an Everton victory come May would be extremely useful for England.

It’s not all about the Champions League teams being eliminated – Europa League is just as important for the coefficient.

Worst-case scenario: what’s the earliest the Premier League could realistically lose its fourth Champions League place?

To wildly predict the future, England’s fourth place will not be affected for the 2015/16 season, should be protected for the 2016/17 season, but may come under threat for the 2017/18 season - but only if Italian clubs consistently out-perform English clubs across both European competitions for the rest of this season and next season.