IT is the burning question on the lips of Saints fans.

In fact, on the lips of football fans whether you follow Southampton or not.

Just WHY do the club find it so hard to keep their crown jewels?

Sadio Mane’s impending departure to – who else? – Liverpool is the latest in a long and depressing line of departures in recent times.

In the last 26 months, ten first team players have left St Mary’s for a total cost of £157m.

That is a staggering list of sales, equating to an average of £15.7m per player.

And it includes Jack Cork and Rickie Lambert, who cost £7m between them.

That leaves the other eight players bringing in £150m between them - an average of £18.75m.

Apart from Cork, who joined Swansea in a bid to find regular first team football, all the players who have left Saints have joined ‘bigger’ clubs.

By that, I mean clubs who play in front of bigger crowds, and who have won more trophies in their history than Saints.

And, as a result, can pay bigger wages.

Lambert, Adam Lallana, Dejan Lovren, Nathaniel Clyne and now Mane have all joined Liverpool.

Luke Shaw and Morgan Schneiderlin moved to Manchester United.

Victor Wanyama joined Tottenham and Calum Chambers moved to Arsenal.

All of those players no doubt moved because they ....

1) Were being offered more money than Saints were paying; 2) Believed their new club would offer a better chance of winning trophies.

While Liverpool actually finished below Saints in the league last season, they did reach two finals – losing both the Europa League final and League Cup final.

As a result, it is hard to believe the likes of Lallana, Lovren or Clyne regret turning their backs on Saints.

But still, the question remains so hard to answer.

Just WHY do the club find it so hard to keep their crown jewels?

Saints have improved year on year ever since returning to the Premier League.

They have qualified for European football two years running. Ok, not the Champions League, but European football nonetheless.

Saints have proved themselves an attractive club for players to join – look at the talent they have signed since Ronald Koeman took charge in mid June 2014.

They have shown they don’t mind splashing out big money on players. Nathan Redmond, after all, was the seventh player to cost the club £10m or more when he signed at the weekend.

Saints obviously pay decent wages, otherwise some of those players wouldn’t have moved to St Mary’s.

And they have proved they can mix it with the Premier League’s elite. In the last three seasons Saints have won at Old Trafford (twice), Anfield, Stamford Bridge and White Hart Lane and put four past the likes of Arsenal and Manchester City.

Last season, Saints only finished three points adrift of a Champions League place.

So much, therefore, to be excited about.

And yet ...

And yet, despite all that, despite all that relative success, STILL so many players (and, lest we forget, two managers) have queued up to leave.

This does not happen elsewhere.

Leicester won the league, finishing 18 points ahead of Saints, and they haven’t sold any of their players this summer.

Indeed, talismanic striker Jamie Vardy has turned down a move to Arsenal to stay loyal to the Foxes.

That is the sort of loyalty rarely seen at St Mary’s in recent times.

Watford last week turned down a bid of £25m for striker Troy Deeney.

Would the Saints hierarchy have done the same?

Will West Ham sell Dimitri Payet this summer? Will any of the clubs who finished above Saints last season sell any of their crown jewels?

We’re not even in July yet and Saints have now sold two – Victor Wanyama and Mane – for a combined fee of £45m.

Fans will fear the exodus will go on after the Euros have finished.

Koeman is already being linked with moves for Fraser Forster and Virgil Van Dijk, while Shane Long will have many suitors after following up his impressive 2015/16 season for Saints with an all-action display in the Euros.

The more you talk about it, the more journalists write about it, the more we come back to the question.

Just WHY do the club find it so hard to keep their crown jewels?

Is it a refusal to break a certain salary cap?

Are the powers-that-be scared of paying beyond a certain level?

Is Les Reed the problem?

But would he like to offer players bigger wages, yet is blocked from doing so?

Is Katharina Liebherr the problem?

Should she either plough larger parts of her family fortune into paying still bigger transfer fees and still bigger wages, or sell the club to someone who will?

Perhaps Saints have just been unlucky with the players they have signed, that they have brought in too many mercenaries.

Mercenaries like Lovren, Wanyama and Mane, who have no loyalty – certainly not the sort of loyalty football fans expect.

But then, if someone offered YOU the chance to double or treble your salary, wouldn’t YOU go?

Money talks.

Saints have confounded all critics in the last two years.

They have continually sold their better players, and have carried on improving their Premier League position.

There comes a point when you can’t do that year in and year out, without something having to change.

For Saints, that time has probably arrived.

When you finish sixth in the Premier League, there are not many more steps to climb.

Saints have given the country’s biggest and wealthiest clubs a few bloody noses in the last three seasons.

As a result, those clubs want Saints’ better players.

That is the way of the Premier League these days.

I repeat - money talks, of course.

It has always talked, but now it screams – and screams louder than ever.

Saints pay good wages, tens of thousands of pounds a week, but that is obviously not enough.

Not enough to persuade their top players to remain loyal for more than a couple of seasons, though.

Not enough to stop fans perennially questioning Saints’ ambition.

To lose one or two star names to bigger clubs every couple of years is the way of the footballing world.

It has forever been thus, and sensible supporters would understand this.

But to lose virtually a whole team of them, within two years, is truly remarkable.

In all my years of following football, I cannot think of one club that has plundered another – in the way Liverpool have plundered Southampton – so often in a short space of time.

There remains only one bit of positive news for Saints fans.

It is this – apart from Cork, all the players who have left have joined glamour clubs. Saints players have not been queueing up to join West Bromwich, Norwich or Stoke.

The day they do, I suppose, is the day fans should REALLY be worried.

However, they are worried now – and rightly so.

How can Saints fans sleep easy at night regarding the future of any of their club’s top players?

Saints have given them so little indication they will ever be able to keep crown jewels for any length of time – be it the manager or players.

That is a huge concern.

Fans need to believe in the people in charge of the major decisions at their club. They need to believe them, and they need to feel they trust them.

Saints have eroded a lot of that trust by their continual selling of top names.

Where will it end? Who else could yet leave?

Questions, questions, questions. Always more questions than answers at St Mary’s.

Again, it has been for ever thus.

But still the one burning question above all others … Just WHY do the club find it so hard to keep their crown jewels?

Why?