The tragic disappearance of the 28-year-old Argentinian striker, who was the Welsh Premier League club’s most expensive signing at £15 million ($19.5 million/€17 million), and David Ibbotson, pilot of the single engine plane that was flying him back to Wales after a farewell visit to his former team-mates in Nantes, has been emotionally marked by the fans of both clubs.

Last Saturday (February 2), Cardiff’s first home match since the accident involved a minute’s silence and a mosaic in the national colours of Argentina formed by fans wearing differently coloured shirts, also spelling out Sala's name.

Tributes had already been paid in Cardiff’s match at Arsenal on January 29, which was to have been Sala’s debut, and at Nantes, where the Argentinian was hugely popular as well as successful.

But behind the emotions, grimly, there is the business of football.

BBC Wales reports that Cardiff have withheld the first scheduled payment until they are satisfied with the documentation.

It is understood Nantes are threatening legal action if they do not receive a payment within 10 days.

A source at Cardiff says they will honour the contract but not until they have clarified "all the facts".

The Welsh club has also registered that it is "surprised" Nantes has made the demand while attempts are being made to recover a body from the wreckage of the plane on the seabed near Guernsey.

By chance, yesterday also marked the anniversary of the Munich air crash of 1958 that claimed the lives of 23 people, including eight of Manchester United’s fabled footballers, three of the club staff and eight journalists.

While manager Matt Busby survived terrible injuries to re-build the team, he had to do so without the core of his "Busby Babes" - England internationals Duncan Edwards, Tommy Taylor, Roger Byrne and David Pegg, wondrous 21-year-old midfielder Eddie Colman, Irish international Liam “Billy” Whelan, centre half Mark Jones and reserve full back Geoff Bent.

United pay tribute annually, and there was a habitual gathering under the Munich memorial plaque at Old Trafford.

The club began the day by posting an image of the side lining up before the match from which they had been returning when the accident happened, along with a message which said: "Remembering the FlowersOfManchester".

The story has been told countless times of how the plane stopped at Munich for re-fuelling after completing the first leg of the journey from Belgrade – where a 3-3 draw with Red Star had secured United’s brilliant young team a place in the European Cup semi-finals - and then slid off the runway and collided with buildings after failing for a third time to take-off amidst snow and slush.

I’ve read numerous accounts of what happened on that wretched day at Munich-Riem Airport, including two from former colleagues in John Roberts – The Team That Wouldn’t Die, the Story of the Busby Babes, Aurum 2008 – and the late lamented James Lawton – My Manchester United Years, the Autobiography, Sir Bobby Charlton, Headline 2007.

More recently I have read James Leighton’s painstaking biography of the player who had established himself as England’s, and perhaps the world’s most promising talents at the time of the crash, Edwards, who was, preposterously, only 21 when he succumbed to crushing injuries 15 days after being hauled from the wreckage of the plane.

Duncan Edwards, The Greatest pulls together a wide-ranging bibliography in telling the story of the young Atlas from the Priory Estate in Dudley who had already earned two League championship medals and 18 England caps at the time of his death.

What tugs at the heart most in this mosaic of recollections is the detail of how the travelling party dealt with the deepening feelings of dread as the intended brief stop-over became less and less brief.

After they had landed in Munich, Edwards himself had surveyed the snowy scene from the doorway and called back to his team-mates in the plane: "Get your snowshoes on lads - short studs are no use in this stuff!"

As the passengers waited in the terminal while the plane re-fuelled, midfielder Eddie "Snake Hips" Colman edged past the seated journalists carrying several mugs of tea for his team-mates.

"Watch it Eddie! You nearly sent the table the wrong way with that body swerve," shouted Eric Thompson, of the Daily Mail, and also of portly build. "It’s a good job I didn’t have to swerve past you Eric," Coleman replied. "I’d still be going!"

Thompson too would fail to survive the crash.

Edwards, sipping tea, was disturbed when team captain Byrne opened the door. "Shut that door, Rog," he said. "It’s freezing in here." At which point Colman and Pegg went into a rendition of Baby It’s Cold Outside.

When the party had to trudge back to the terminal through the slush after two attempts at take-off had been abandoned, the mood, in Charlton’s recollection, had "dipped".

In an effort to lighten the atmosphere back in the terminal, the small and rotund Thompson tried on the massive overcoat of fellow journalist Frank Swift, the 6ft 2in former Manchester City goalkeeper and shuffled around pretending to be a grizzly bear.

Swift, who died later that day on his way to hospital, also raised a few laughs as he attempted without success to get into his smaller colleague’s coat.

At one point a rumour went through the terminal that they would have to wait until the next day to get back to Manchester. Edwards, who had been hoping to meet his girlfriend Molly that evening, rushed to the phone and delivered a telegram to his landlady: "Flights cancelled. Flying Tomorrow – Duncan."

But then came the announcement on the tannoy: "Could the Manchester United party please re-board?"

United’s pioneering appearances in the new European Cup  competition in 1956-1957 and 1957-1958 went against the wishes of the then Football League secretary, Alan Hardaker, who feared it would become an unwelcome distraction from home matches. Chelsea, Football League champions in 1955, were dissuaded from taking part, but Busby was determined that United’s future lay in European competition.

Hardaker was forced to relent - but the Football League reserved the right to fine and deduct points if teams failed to return from away matches in Europe leaving insufficient time for Football League fixtures.

And Busby knew that delay might incur punishment at the very point in the season where his team was seeking to hold off the challenge at the top of the table from Wolverhampton Wanderers, who were their opponents in the next match.

In the awful aftermath, these ambitions and arrangements and accommodations gnawed away at Busby as he struggled to deal with an enormous sense of guilt. History records that he overcame these destructive emotions to see United lift the European Cup a decade later.

Football and business. It can sometimes be a grim mix.