Essex opener Sir Alastair Cook unleashed his indefatigable class on Somerset as England’s greatest Test run-scorer unfurled a century in the Bob Willis Trophy final.

North Somerset Times: Essex's Alastair Cook celebrates with with teammate Tom Westley after scoring a century during day three of the Bob Willis Trophy Final at Lord's, London.Essex's Alastair Cook celebrates with with teammate Tom Westley after scoring a century during day three of the Bob Willis Trophy Final at Lord's, London. (Image: PA Wire/PA Images)

Former England captain Cook mixed grit with pragmatic elegance to reach 172, his second century of the season, and the 67th of his first-class career.

He was joined in a 170-run second-wicket stand by Tom Westley (51) as Essex headed towards a first-innings lead while pushing Somerset into the dust at Lord’s.

But, like on the second day, late wickets with the second new ball evened up the contest as Essex ended the third day of the five-day match on 271 for six, trailing Somerset by 30 runs.

Cook has scored more Test runs at Lord’s than anyone other than his mentor and idol Graham Gooch, it is also the ground he has graced 34 times in first-class cricket – only the Cloudfm County Ground, Chelmsford has seen more of him.

North Somerset Times: Somerset's Lewis Gregory celebrates with teammates after the dismissal of Essex's Nick Browne (not in picture) during day three of the Bob Willis Trophy Final at Lord's, London.Somerset's Lewis Gregory celebrates with teammates after the dismissal of Essex's Nick Browne (not in picture) during day three of the Bob Willis Trophy Final at Lord's, London. (Image: PA Wire/PA Images)

It seemed inevitable that on a grand occasion he would step up for his county and shine.

Nick Browne, who had been left out of the last two Group stage matches, departed almost exactly an hour into play when he edged Lewis Gregory to Craig Overton at second slip.

Meanwhile, Cook’s innings had begun in typical Cook fashion – completely risk averse, and only permitting glances, cuts and defensive shots – and only strayed from his tried and tested methods later in his knock with short bursts of scoring.

He grew into his innings and found beauty in cover drives, particularly off Josh Davey, as he reached his fifty in exactly 100 deliveries.

North Somerset Times: Somerset's Craig Overton bowling during day three of the Bob Willis Trophy Final at Lord's, London.Somerset's Craig Overton bowling during day three of the Bob Willis Trophy Final at Lord's, London. (Image: PA Wire/PA Images)

The next milestone was reached in 64 more deliveries brought up when Jack Leach gifted him a full toss outside his off stump for his 18th four.

Impressively 46 of his first 100 runs came through the cover region, 11 of which in boundaries.

Cook belied the Baltic conditions – typified by a howling wind which threatened the flag poles on the pavilion and saw umpire Russell Warren lose his hat while turning down an appeal – by wearing short sleeves.

During the course of his vigil, Cook rose to 142nd in the list of all-time leading run scorers in first-class cricket – overtaking Steve Waugh, Ray Illingworth, Ricky Ponting and Sadiq Mohammad.

North Somerset Times: Somerset's Jack Leach bowls during day three of the Bob Willis Trophy Final at Lord's, London.Somerset's Jack Leach bowls during day three of the Bob Willis Trophy Final at Lord's, London. (Image: PA Wire/PA Images)

And he also leapfrogged Worcestershire’s Jake Libby as the leading scorer in the Bob Willis Trophy as he steamed past the 500-run barrier of the campaign, eventually nestling on 532.

Cook, who retired from international cricket two years ago, also now boasts more non-Test centuries than Test.

For three and a half hours, Cook had a trusted accomplice in Westley, whose batting had endured a woeful season, after the right-hander had been handed the Essex captaincy.

After only 121 runs in the Group Stage, something clicked for him at Lord’s, the venue of his final of five Test appearances.

Like Cook, he was largely unmemorable in his run-scoring although found a penchant for flicking full deliveries off his legs on his way to a 128-ball half-century, his first in a year.

Westley fell following a 170-run stand with Cook, comfortably bettering Essex’s previous best competition stand of 86, when he clipped Tom Lammonby to Tom Abell at square leg to the second ball after tea.

Dan Lawrence came and went soon after when he clothed a pull shot to midwicket off Gregory and Paul Walter was lbw to the following delivery.

A full-blown collapse was averted by Ryan ten Doeschate before he was lbw to Overton with the second new ball, while Cook reached 150 in 250 balls with a quick single to mid-off.

Cook did depart, after 384 minutes, with five overs left in the day when he prodded to a stooping Overton at second slip to hand Gregory his fourth – he ended the day with 4-58.