Sam Robson took two wickets in two balls with his occasional leg spin to spark a remarkable 190-run Middlesex victory against Surrey deep inside the final hour of a gripping Bob Willis Trophy London derby at the Kia Oval.

Surrey looked to be holding on quite comfortably for the draw after tea, with Rikki Clarke and Jordan Clark defending resolutely through 23 overs.

But, with 16 overs remaining, Robson was thrown the ball by Middlesex’s acting captain Stephen Eskinazi and, with his fourth and fifth deliveries, he removed Clark and Dan Moriarity in dramatic fashion.

Clark, having made seven from 66 balls, chipped back a long hop and then an ecstatic Robson pinned Moriarty leg-before with a looping leg break which hit the left-hander on the foot as he played forward.

Suddenly, with Surrey 119 for 7 rather than 119 for 5, Middlesex smelled blood and it was their former West Indies fast bowler Miguel Cummins who swept them on towards their 22-point triumph, first having Matt Dunn superbly held for nought at short leg by Max Holden as he fended off a vicious lifter and then bowling James Taylor for four with an inswinger.

Clarke, desperately looking to claim the strike with last man Amar Virdi now in, advanced to the fifth ball of the 63rd over – bowled by Nathan Sowter – and the leg-spinner cleverly fired it through the batsman’s legs for keeper John Simpson to gather and complete the stumping as Clarke tried in vain to scramble back into his crease.

Clarke, Surrey’s acting captain, made 22 from 104 balls.

The last five Surrey wickets had tumbled for four runs in seven overs and, with 8.1 overs remaining, Middlesex could celebrate a famous win against their greatest rivals.

Robson, who had only previously taken four first-class wickets at almost 50 runs apiece, was given two more tidy overs following his memorable intervention and finished with figures of 3-3-0-2 and the impressive Cummins took 3 for 30.

Earlier, Surrey had lost three wickets in as many overs just before lunch, which they took on a wobbly 20 for 3 after Middlesex had set them 314 to win in 71 overs.

But then they recovered through a 64-run stand between Ryan Patel and Jamie Smith before both fell to short balls from James Harris and Cummins respectively in the 30th and 33rd overs.

Patel could not believe it when he swung a short ball from Harris high to deep mid wicket to go for 44, while Smith reached a classy 40 before touching a lifter from Cummins, angled across him from around the wicket, as he tried to get his bat out of the way.

Mark Stoneman had been the first Surrey batsman to fall, leg-before to Murtagh for four as he prodded defensively forward to the veteran seamer and then, in the next over and with his first ball of the innings, left-arm spinner Thilan Walallawita struck a further blow by having Scott Borthwick smartly taken by wicketkeeper Simpson for one as he flicked at a ball turning past his pads from over the wicket.

Then, on the stroke of lunch, Murtagh came in off a shorter run to nip one back through Will Jacks’ defences to bowl him for a duck with the fifth ball of the 11th over.

Surrey, who had lost their last seven first innings wickets for just 28 runs on day three, were suddenly fighting for survival rather than dreaming of a glorious victory chase.

Moriarty, a 20-year-old slow left-arm spinner born in Reigate but raised in South Africa, had earlier taken 5 for 64.

Like fellow left-arm spinner Walallawita, he was making his first-class debut and already had 3 for 39 overnight. But he impressed again on the fourth morning of the match after Middlesex resumed their second innings on 184 for 3 looking for quick runs.

Nick Gubbins added just 11 to his overnight 49 before being bowled by Moriarity in extraordinary fashion. Aiming a premeditated reverse sweep, the left-hander lost his balance and was on his hands and knees in the crease as his middle stump was uprooted.

Martin Andersson, resuming on 35 and completing a half-century with successive fours off Virdi, went for 51 from 62 balls, with 10 fours, when he lifted a catch to short extra cover off a leading edge to give Moriarty his fifth scalp.

Simpson mishit Virdi’s off spin to deep mid wicket to go for 18 before Sowter came in to keep Harris (17 not out) company before the declaration came at 248 for 6 after an hour’s play at 12 noon.