Lancashire 304 for 4 (Jennings 96, Vilas 70*) beat Middlesex 284 (Harris 117, Simpson 74, Mahmood 4-38) by 20 runs

There is, in case you missed it, quite a kerfuffle at present about the sudden availability of a genuinely quick new-ball bowler, a man with the potential to add a new level of pizzazz to England's World Cup attack. But not even in his wildest dreams could Jofra Archer hope to hoover up 25 wickets at 18.88 in his first nine matches of the tournament, to propel his team into the semi-finals.

Saqib Mahmood has done just that for Lancashire in the Royal London Cup. In spite of a startlingly heroic fightback led by James Harris, whose maiden List A hundred included a sixth-wicket stand of 197 with John Simpson that carried a spirited chase deep into the penultimate over, the ferocity of Mahmood's new-ball burst was an intervention that could not be patched over in the final analysis.

It was, nevertheless, the most improbable sporting thriller since … well, the midweek Champions League fixtures. Somehow, Middlesex clawed their way back from oblivion at 24 for 5 in the tenth over, as a batting line-up that had been denuded by injury and international call-up - with Paul Stirling, Dawid Malan and Eoin Morgan all missing from their first-choice XI - instead found itself relying on a makeshift No.6 whose previous highest List A was a paltry 32.

Harris arrived in the middle with his side in freefall and Mahmood enjoying the ultimate Master-and-Apprentice learning experience alongside the ageless Lord of Lord's, Jimmy Anderson, who produced yet another Pavilion End masterclass, and even topped and tailed his day with a pair of direct-hit run-outs.

Screaming to the crease with the biomechanical purity of Brett Lee, allied to a splayed-limb final flourish that evoked Waqar Younis in his pomp, Mahmood blew away Sam Robson and Stevie Eskinazi - the latter to a rabbit-in-the-headlines hook that spiralled to square leg - before producing an off-stump snorter that a batsman with the class and form of Ross Taylor could only steer to slip.

The game was a goner - and long before half-time this time - so Harris decided to trust both his eye and his partner, and enjoy the rare opportunity to set out his stall for the bulk of a 50-over innings.

For a full 30 overs, he thrived - bossing the change bowlers, not least the legspinner Matt Parkinson, on a pitch that Lancashire's own batsmen had already demonstrated was full of runs. Without ever exerting themselves, Lancashire had eased to a total of 304 for 4, with Keaton Jennings' 159-run stand with Stephen Croft providing the backbone before Dane Vilas' 70 not out from 67 had applied some late urgency.

However, it seemed for a long while that Lancashire would regret not getting more of a wriggle on against a Middlesex attack lacking the senior statesmen, Steven Finn and Tim Murtagh, and which at times seemed to be relying on a combination of bluff and guts to stay in touch. No-one had epitomised that better than the medium-pacer George Scott, whose early diving catch at midwicket to remove Liam Livingstone was the outstanding fielding moment of the day, and whose looping leg-stump yorker somehow wriggled into Jennings' timbers to extract him for 96 and complete a notable maiden List A wicket.

But Harris simply kept his composure, and once Mahmood and Anderson had been withdrawn after six overs each, he correctly ascertained that by batting through the overs, the runs would have to come on a pitch as true as Lord's. He brought up a superb century from 90 balls, with nine fours and two sixes in consecutive overs off Parkinson and Graham Onions, and the increasing frequency of Lancashire's brains trust gatherings was a clear indication of their mounting doubts.

But then, in the 41st over, everything changed again. Swinging across the line to Parkinson, Harris let his back foot twitch fatally as his toe strayed out of the crease, and then two balls later, calamity struck, as the new man, Scott, slapped an inside-out drive to mid-off, and sold Simpson a dummy as Anderson's dead eye pinged down the stumps at the far end.

Though Scott made amends as best he could, with Toby Roland-Jones also digging deep in an eighth-wicket stand of 45, Mahmood would not be denied. Back he came at the death, finding his yorkers at will to strangle the scoring rate, before earning a somewhat fortuitous fourth wicket, as Scott was pinned on the knee-roll by an inswinger, albeit outside the line.

With the situation getting frantic, Nathan Sowter ran himself out with a suicidal single to the keeper, before Roland-Jones picked out deep midwicket one ball later to end Middlesex's spirited campaign. It's been 31 years and counting since they last won a List A title - but there has been much to admire in their white-ball endeavours this year.

Lancashire, meanwhile, march on to face Hampshire in the semi-final on Sunday, and with a world-class strike bowler bubbling up in their ranks, they may yet believe that this hard-fought win was but a dress rehearsal for their own overdue return to trophy-winning ways at Lord's.