Surrey 262 and 278 (Patel 107, Smith 70) beat Essex 180 (Walter 64, Clark 3-33, Worrall 3-40) and 215 (Elgar 60, Lawes 4-26) by 145 runs
Tom Lawes was Surrey's last-day hero with four for 26 as they bowled out Essex for 215 to complete a 145-run victory over their nearest rivals at the Kia Oval and increase their lead at the top of the Vitality County Championship table.
Dean Elgar scored a typically defiant 60 but Surrey's quicker bowlers chipped away relentlessly once morning rain had cleared, with 21-year-old tyro Lawes first taking two wickets in successive balls and then returning after tea to break further Essex resistance from Paul Walter and Michael Pepper.
Surrey's 20-point win, their sixth from nine Division One matches so far this season, was completed with 25.5 overs to spare and they remain on course for three championship titles in a row. In support of Lawes, Jordan Clark finished with three for 56 and Dan Worrall two for 71.
Second-placed Essex, rightly, will be sore that they effectively had to play a vital top-of-table fixture with ten men due to the absence virtually throughout of Jordan Cox, who left the field early on day one feeling unwell. Cox has since had an operation to remove his appendix but ECB regulations allow a substitute only for concussion victims.
Perhaps Cox's full involvement might have made little difference, particularly on a well-grassed pitch that encouraged the seamers throughout, but the 23-year-old came into the game heading Essex's championship batting averages with 763 runs at 69.36. Losing him to illness was unfortunate enough, but not be able to replace him with another batsman in such circumstances meant Surrey also had to take just 18 wickets overall, not 20.
Resuming their second innings on 21 for two, Essex would have been aiming only for survival, rather than an improbable chasing down of a 361-run win target, and a two-hour bad weather interruption early in the day certainly helped their cause.
Only 13 balls were bowled at the start, Essex moving quickly to 38 for two as Westley took two fours from Clark's opening over, before rain ruled out a resumption until after an early lunch at 1.10pm.
Elgar and Westley then initially flourished - once Westley had survived a huge early shout for leg-before when a Worrall outswinger squared him up and thudded into his back pad - and the pair took their third wicket alliance to 69 before Lawes' introduction dramatically swung the contest back in Surrey's favour.
Worrall had been taken for three offside fours in one over by Elgar, while Westley off drove Clark elegantly for four before flicking Worrall away for further boundaries to fine leg and then off his pads to square leg.
But, with his second ball, after replacing Worrall at the Vauxhall End, Lawes had Elgar dropped by Dom Sibley at second slip on 36 before, in his second over, removing both Westley and Matt Critchley.
Each time Ben Foakes dived to his right to take good catches as perfectly-pitched outswingers took the edge of both Westley and Critchley's forward defensive bats and, suddenly, Essex were 86 for four with Lawes on a hat-trick.
He had to wait until the first ball of his third over for the hat-trick opportunity, only to see Elgar clip away a full ball to deep mid wicket for three to complete his half-century.
Lawes' six-over spell of two for 18 had, however, seriously damaged Essex's hopes of batting out the day for a draw and, when Worrall returned to replace Lawes in the attack and tempt Elgar into hooking a short ball straight into deep mid wicket's hands it looked as if the end was nigh for the visitors.
Walter and Pepper, though, added 64 until Lawes struck again with the sixth ball after tea to have Pepper held at second slip for 26, and the young fast bowler then bowled Walter for 56 - via an ugly under-edged pull to a ball that was not there for the shot - to leave Essex 194 for seven.
Simon Harmer (7) hung around bravely for 42 balls before edging Worrall to Foakes and the next ball, Clark's first of the following over, pinned Shane Snater lbw for seven to wrap up Surrey's win.
An overall attendance for the match of 13,706, meanwhile, boosted considerably by the 6,300 who turned up to support the club's Festival of Red Ball Cricket initiative on day one - when the Oval concourses were offering a wide variety of family-friendly activities - is a ground record for a Surrey championship fixture this century.
