Heard the one about green cricket balls? It's no joke, just the latest suggestion for helping Test matches to move out of daylight hours and into the night.

For anyone wondering whether locating the ball in the outfield might prove tricky, the 'green' in question is of the lime variety.

Members of the International Cricket Council, who assembled at Lord's this week, were shown examples of a green ball that will be tried out in a trial match soon as manufacturers try to come up with a perfect projectile for use under floodlights and when white clothing is being worn.

That is the main challenge for supporters of day-night Test cricket which could be coming to Lord's as early as next year.

A red ball will not do because players are agreed that it cannot be seen properly under lights. And white is out because officials are determined that Tests must continue to be played by people wearing traditional clothing.

Pink could be the new red and that colour ball will be tried out again today during a club match at Lord's, but the jury is still out on that one. So what about a green ball? Or yellow? Or a nice shade of lilac? "Research on developing a ball is progressing well," said Haroon Lorgat, chief executive of the ICC. "The sentiment of the committee over day-night Tests is supportive. But we want to get some hard facts on that."

The MCC are already talking about trying to stage a first-class day-night match at Lord's this season. And with the ICC open to the idea of a five-day (and night) trial game under lights as early as 2010, the possibility of England's Test against Bangladesh next May creating history by stretching into the dark cannot be discounted.