LEGENDARY batsman Jimmy Cook helped ensure two Somerset records he set were erased from the history books as his county slaughtered Glamorgan.

Cook scored 136 not out against the welsh county at Neath in a Sunday League game in 1990. Somerset's total was 360-3 and they won by 220 runs – both achievements remained the club's best in 40-over cricket until Saturday.

At Taunton, on Saturday, Somerset scored 368-4 and won by 249 runs. Cook was again at the heart of it.

The former opener is now Somerset's batting coach and it was his hard work with Pete Trego that helped the England Lions all-rounder hit his highest score in any form of the game – 147.

Jos Buttler made a one-day career best 90 not out and Glamorgan were swept out for 119 to set up a Clydesdale Bank 40 semi-final at home to Essex this Saturday.

Trego thanked Cook for his help. "I have been working with Jimmy Cook on the fundamentals of batting," he said. "My strength is my strength and the fact that I am good hitting straight. I have just been working on hitting it hard and straight and not trying to get too funky."

Trego's attempt to tope-edge seamer Will Owen over short-third man only to be caught by the fielder saw him dismissed, but by then he had more than justified his promotion to open the batting with Marcus Trescothick.

"I feel it is a role I can do well and myself, Tres and (coach) Andy Hurry have been rowing about it for years," he said. "I sometimes feel a bit wasted at the bottom, but the guys who do a job at the top do a great job. It is nice to put my name in the hat if the opportunity comes up."

Having reached his first 50 in the power-play off 27 balls, Trego needed 42 more deliveries to go to a maiden one-day hundred.

He gave one half-chance on 116, when Gareth Rees dropped him one-handed on the run on the deep square leg boundary.

Two more big sixes helped him past the 140 he scored in a first-class game against West Indies A in 2002 as he finished with 19 fours from 89 deliveries.

"He has been gagging for an opportunity in the last few weeks in one-day cricket and we have given him the chance," said Trescothick.

"It was an absolutely fantastic knock and it was a joy to bat with him. His running between the wickets is a bit suspect at times but when he strikes it out of the park like he does there are not many people who can do that.

"He is getting ever closer (to a senior call). Knocks like that will really help his career. After seeing that, we might give him more opportunity to bat at three.

"If one of the top three can do that, it means we are a good strong team. If he keeps doing it, he has got every chance. That is what the selectors look for – 140s and 120s give you a good chance."

Buttler savaged Glamorgan's bowling, striking his 90 not out from 33 balls, while James Hildreth stroked an unbeaten 58.

Glamorgan's feeble response saw Ben Phillips take 4-31 and Murali Kartik 3-23.