When Kerry Packer arrived with World Series Cricket (WSC) in the late 1970s he took many of the world's best players, dressed them up in brightly-coloured clothing and gave them a white ball. It heralded the end of several test careers, with players opting for a lucrative retirement fund. It also threatened to change the game of cricket forever.

Looking back now, the legacy of WSC goes no further than the bright clothing and white ball. The cricket World Cup began before WSC and simply incorporated these innovations, beginning with the 1992 World Cup where England wore a terrible powder blue outfit but still managed to reach the final.

Yet Test cricket largely survived the Packer years intact. While there is more one-day cricket played internationally than there was before, some sparkling series and eras of great teams from the West Indies and Australia have made Test cricket the pinnacle of the game in the last three decades.

But now another threat looms large. Twenty20 cricket is a different breed. Whereas one-day internationals are a slimmed-down form of Test cricket - a 20 per cent version if you will - Twenty20 cricket is a whole new ball game. There is no time for hesitation, no time to play yourself in, it is crash, bang, wallop cricket at its adrenaline-fuelled extreme.

The game fits into an evening, is accessible for even the shortest attention spans and rarely has a dull moment. That attracts a different audience to longer forms of the game - a fact not lost on proponents of the format.

Test cricket has a heritage and history that is rich and deep. There are the greats of the game who dominate the record books, but there are also only nine current Test playing nations and, in a global sporting market place, the wider reach of Twenty20 cricket could be the crucial difference between being a niche sport and a mainstream one.

Sir Allen Stanford is quoted as saying he finds Test cricket boring and he thinks many others do too. The advent of Twenty20 cricket, then, is a direct threat to the long form of the game. If the money follows the mainstream opinion, Test cricket could end up marginalised; an outdated mode of the game that still has its fans, but not the attention of the masses. Any ensuing withdrawal of sponsorship or television interest could prove fatal to the sport.

The main difference between Twenty20 and other forms of the game in sporting terms is the lack of opportunity for natural ebb and flow to occur. The game is so short that, save for a poor batting display being rescued by an excellent bowling one or vice versa, there is no room for changes in momentum. It is these changes that are often the cause of great memories and great matches, take the second Test between India and Australia in 2001 as a prime example.

The one great hope is that the spectators drawn into Twenty20 can be taken in by the game to such an extent that they are only delighted to find versions of the same sport that last even longer and have even more plot twists. Surely even the most impatient sports fan would have enjoyed the 2005 Ashes series, when the many twists, turns and tight finishes brought Test cricket back to the front pages again - just in time for the new threat from Twenty20.

This is what makes Test cricket a great sport as far as I am concerned, and it is the specific loss of this depth that makes Twenty20 cricket less appealing to me. The potential loss of Test cricket as it gets dwarfed in the fight for TV rights and sponsorship is very worrying for every cricket fan, yet the future of Test cricket is likely to be determined by the people who do not like the sport.