Jamie Porter recorded career-best match figures of 12 for 95 to strengthen Essex's hand at the top of the Specsavers County Championship with an embarrassingly comfortable victory over Division One strugglers Somerset.

The Chingford CC seamer followed up first-innings figures of five for 40 with his best innings return of seven for 55 in the second, and in the process passed 50 Championship wickets for the third season in succession.

Of greater significance, Essex's fifth win in a row gave them a 36-point advantage over second-placed Lancashire ahead of the top-of-the-table match at Old Trafford, starting on Tuesday.

After Adam Wheater's season-high 88 and Ryan ten Doeschate's 67 left Somerset to chase 289 at just under five an over, they succumbed for 109 inside 38 overs.

Leytonstone-born Porter was almost unplayable from the Hayes Close End and struck with the second ball of the innings, Marcus Trescothick chopping on.

There might have been another in Paul Walter's first over, but Varun Chopra's view of an edge from Eddie Byrom might have been obscured by James Foster's dive.

It mattered little in the long run as Porter claimed the second wicket in his next over, swinging one in to Tim Rouse to take the edge on its way through to James Foster. The same combination accounted for Byrom, at which point Porter had three for 15 from 19 deliveries.

Simon Harmer entered the fray in the next over and with his third ball had Tom Abell playing no shot to be judged lbw. James Hildreth laid into the Essex attack with 22 from 22 balls before he followed one from Porter and was caught behind.

Craig Overton and Steven Davies put on 39 for the sixth wicket but the return of Porter in the first over after tea signalled the end of Davies, essaying a shot through midwicket but edging to Nick Browne at third slip. It was Porter's 10th wicket in the match, beating the nine for 160 he posted against Surrey on the same ground at the end of May.

Dom Bess followed swiftly, the latest batsman this season to offer no shot to Harmer and look surprised to be given lbw.

Porter's career-best sixth wicket in an innings arrived in his 11th over when he came around the wicket to beat Jack Leach for pace. Tim Groenewald failed to get a bat on another express delivery for number seven before Harmer bowled Overton for a top score of 36.

Earlier, Essex advanced their lead by 126 runs in an entertaining 29-over morning session. Ten Doeschate, who had come in just before rain curtailed the third day, rattled off an enterprising 67 from 89 balls before he was seventh man out to the last ball before lunch.

During that time he was the guiding force in stands of 77 for the fifth wicket in 20 overs with Wheater, and 50 from nine overs with James Foster for the sixth as, having survived an early caught-and-bowled chance that gave Tim Groenewald a painful rap on the knuckle, he made the most of his good fortune.

Wheater reverted to the role of second fiddle in a stand that went past 50 in 13 overs. He pulled Paul van Meekeren sharply through midwicket for his 11th boundary before he chased an outswinger from Craig Overton and was caught behind. He had faced 188 balls.

A wristy late cut off Van Meekeren gave Ten Doeschate his fourth four and a scampered two into the covers next ball carried him to a 76-ball half-century, before he brought up the fifty partnership with Foster via successive fours off Groenewald.

Foster too landed some lusty blows before he went lbw to Groenewald and with no addition to the score, Ten Doeschate pushed forward to Jack Leach and was snapped up by Trescothick at slip.

Essex batted on for 15 minutes after lunch, adding 10 for the loss of Harmer and Porter, both to young spinner Bess. With Mohammad Amir absent hurt it was the end of the Essex innings on 293.