Flintoff's brief innings provided what little entertainment was available to a 4,000 crowd in a surprisingly one-sided game that finished an hour- and-a-half early.
Last season these counties occupied the top two places in the table, but Warwickshire never came to terms with a difficult pitch and an accurate Lancashire attack.
Seamer Peter Martin made the most of the unreliable surface as he took 5 for 28, including the last four wickets and the Sri Lankan off-spinner Muttiah Muralitharan again proved almost unplayable. He took 14 for 117 in the Championship game between the same sides at Southport last week, and he conceded only 13 runs from nine overs in his first National League bowling stint.
Only two Warwickshire batsmen, Nick Knight and Graeme Welch, looked comfortable, but they needed all but two balls of their 45 overs to scrape together an inadequate 127 runs. Ed Giddins gave Warwickshire a glimmer of hope when he bowled Mark Chilton and had Mike Watkinson caught at square leg. But Flintoff put the game beyond doubt when he crashed 20 off one over from Giddins with two huge sixes and two fours.
Flintoff fell to Dougie Brown, but the Lancashire captain John Crawley finished the job with an unbeaten 34.
Michael Di Venuto fired an unbeaten 72 as Sussex maintained their 100 per cent record in Division Two, overpowering Durham by seven wickets. Sussex, set a modest target of 162 at Hove, romped home with more than 19 overs in hand to record their fifth straight win.
The Tasmanian left-hander Di Venuto, who has played in nine one-day internationals for Australia, shared an entertaining second-wicket stand of 126 in 16 overs with his captain Chris Adams, who made 64 from 47 balls. The Sharks' chase got off to a poor start when Richard Montgomerie was run out for five in the second over.
However, Di Venuto and Adams put the hosts on their way to an emphatic victory with some attractive stroke play, and Adams had smashed nine fours - and a six off Michael Gough - when he played on to the former Sussex off-spinner Nicky Phillips.
Durham have now lost their opening six games and they crashed to their lowest League score of the season, being dismissed for 161 with 15 deliveries of their innings remaining. The visitors, without captain David Boon with a badly bruised hand, and wicketkeeper Martin Speight due to a broken finger, lost wickets steadily after John Morris and Paul Collingwood shared a second wicket stand of 72 in 11 overs.Reuse content