The mere fact that Crawley Town will take their place at Old Trafford to play Manchester United should encapsulate the unifying soul of football, as nourished by the FA Cup. Battered, often undermined by the profile and financial might of the Premier and Champions Leagues, on days like these the FA Cup reminds us that the game remains one.

The competition that began in August, with clubs such as Billingham Synthonia and Glossop North End contesting the extra preliminary round, travels by the inexorable logic of knockout to the greatest names and arenas of football.

In Crawley, the small, dormitory Sussex town dominated by unloved Gatwick airport, the thrill is unconfined: 9,000 people, more than four times a decent crowd for the club's Conference Premier fixtures, have forked out the £41 United are charging to watch Steve Evans's team in the fifth-round tie.

Yet around non-league football, among other Conference clubs and their supporters, there is a low grumbling, a resentment that of all clubs, Crawley's number came up; a feeling that they do not, in fact, embody the romance of the Cup.

In part this is due to Evans himself, who has proved himself a smart non-league manager, but made himself deeply unpopular. The FA banned him from the touchline for 12 matches in 2008-09 for improper conduct and 13 in 2009-10, including three when he was not even allowed in the ground. In November 2006 Evans was convicted for his part in a £245,000 tax fraud committed when he was manager at Boston United, failing to pay tax on the players' wages, and was given a 12-month prison sentence, suspended for two years.

Evans and Crawley accept he has form, but argue he has served his time and is proving his talent. His club are three points behind AFC Wimbledon, the leaders of the division now known as the Blue Square Bet Premier, with four games in hand and relishing their jackpot FA Cup run.

If a heartfelt cheer about Crawley is withheld, it is also because their rise has been fashioned with sudden new money. Huge transfer fees for this level, estimated at £600,000, have been spent since the summer on the striker Richard Brodie from York City, the midfielder Sergio Torres from Peterborough United, and others, with a wage bill to match. Yet despite the media floodlighting the club since their Cup wins began, they have still refused to say who has provided the money, except that it is a group of people in "the far east". Bruce Winfield, the Crawley chairman who, with his wife Silpa, is a major shareholder, told the Guardian's Digger column that these far east investors now own 40% of the club. However, he has not identified them, explained where their money has come from, or why they want to remain anonymous.

After so many financial meltdowns at all levels it is widely accepted that it is important to know who owns football clubs and the fact that Crawley Town are substantially owned and funded by anonymous investors steals a little romance from this tale. That United, arguably English football's most storied name, are owned by the Glazers, who recently reorganised the club's ownership into the US state of Delaware, where shareholders can also remain unidentified, completes the flipside of the tie's allure.

This week Susan Carter, Winfield's fellow director, again declined to say who the club's backers are. Asked about their spending, on transfer fees and players' wages said to be around £100,000 a year for some, Carter replied: "How many clubs actually spend what they make in income? Very few. It's a problem in football; we're only doing what other clubs are doing."

Crawley fans know themselves the perils of financial mismanagement. The club collapsed into administration in 1999, then in 2006 when it was owned by the brothers Chas and Mohammed Azwar Majeed, the latter of whom was subsequently convicted of tax fraud and sentenced to three and a half years in prison.

Crawley were only an hour from being wound up when the administrators accepted a proposal to pay creditors half the £1.375m they were owed. The club was taken over by John Duly, a local businessman, then Vic Marley, an ex-banker and Crawley supporter, via his Prospect Estates Holdings company. Winfield, a Crawley-based businessman and prominent fan for many years, took over the club with Carter in 2009. In July last year Prospect Estate Holdings transferred all its 45 shares in Crawley Town to Winfield's wife, Silpa. Although Winfield has said the club is now 40% owned by the far east investors who have put the money in since last summer, there is no record yet of their shareholding in the club's official documents filed at Companies House.

Alan Williams, Crawley's chief executive, says he has met the investors and is satisfied their money is sustainable.

"I came in to turn the club round after the Majeeds' era," Williams explains. "The investors have put the money in, and there is a long-term plan. They have a right to anonymity. There is nothing conniving or devious about it."

As for why people in the far east would put their money into Crawley Town, Williams says: "They have an interest in football, and a difference can be made here."

Jeff Thadeus, secretary of the Crawley Town supporters trust, says after the trauma of the Majeeds, he and the supporters feel safe with Winfield. "We'd rather the anonymous investors were people we know," he acknowledges. "The combination of that and Steve Evans means people are bound to snipe. But we have to put our faith in Bruce. This is a great day for the club, and the town, which can feel part of it again."

FA rules require Conference club directors, and owners of 30% or more of the shares, to self-certify that they are "fit and proper people," with no convictions. An FA spokesman said Crawley have complied, but did not explain whether in fact any of the new investors individually owns 30%.

Dave Boyle, chief executive of Supporters Direct, argues that owners of football clubs, public sporting institutions drawing on the support of their towns, should not be entitled to hide behind anonymity.

"Crawley is not such a romantic story and they are not a typical non-league club," he says. "It's an all-too-familiar tale of financial doping and opaque ownership, and we have seen too many of those ending in collapse down the years."

Dennis Strudwick, general manager of the Conference, confirms Crawley have complied with all the rules, in a league which has experienced many clubs in various shades of crisis. "This is wonderful," he says, "to see a Conference club in the fifth round against Manchester United. We should be talking about the beauty and romance of the FA Cup, but instead the questions are all about finance."

That is because Crawley Town are at Old Trafford thanks to skill and hard work, but also big money from unidentified backers. They play Manchester United, owned in Delaware by the US family which loaded the club with £500m debt. That, too, is an integral part of this, a perfect FA Cup story for our times.{jcomments on}