The rain-affected match was set for a thrilling finish after the first day when Lancashire, chasing 138 for victory, slumped to 70 for 6 before rain halted play. More heavy rain prevented the match resuming until 4.20pm, but it then descended into confusion as bad light forced the players from the field again.
At that stage Lancashire were 107 for 7 from 25 overs - the cut-off point when a game can be decided on faster scoring rate. Lancashire were ahead on that count when the light was offered immediately at the end of the 25th over and there were cries of "cheat" as the players headed for the pavilion.
But one of the umpires, Trevor Jesty, insisted: "The 25 overs did not come into it. We offered it because it was bad light, that's all. We had been watching the light for the previous two overs and it just got bad very quickly."
When the umpires decided conditions had improved, Lancashire's target had been reduced to 121 from 44 overs and Warren Hegg and Ian Austin quickly wrapped up the county's third group A victory.
Northamptonshire's hopes of improving on their third place in last year's Britannic Assurance Championship have been hit by an injury worry over their West Indies paceman Curtly Ambrose.
Northants travel to Durham in the opening round of games today without their overseas player, who is due to arrive back in England this weekend. But he has picked up a knee injury in the current Test against New Zealand and the county are unsure when he will be available.Reuse content