A return of four for 43 by Richard Pyrah, who also featured in two run-outs, helped Yorkshire defeat nearest rivals Gloucestershire by 23 runs at Headingley to increase their lead at the top of B Division in the Clydesdale Bank 40 League.

Yorkshire have now won eight of their nine matches to go four points clear of Gloucestershire, who have a game in hand.

Will Porterfield and captain Alex Gidman began Gloucestershire's run chase towards a target of 248 in determined fashion, Gidman punishing Ajmal Shahzad with a six over mid-wicket followed by two cuts for four in the same over and Tim Bresnan also proving expensive as Porterfield glanced him to the boundary and hooked him for six.

Gidman survived a low caught-and-bowled chance to Steven Patterson on 35 but, having contributed 48 out of 76 by the 12th over, he drove Pyrah to Anthony McGrath at mid-on.

James Franklin was bowled in Pyrah's next over to bring in Hamish Marshall and he and Porterfield added 50 in 10 overs before Porterfield took a step down the track to Adil Rashid and was stumped by Gerard Brophy for 53 from 72 balls, which included five fours and a six.

It was Pyrah who swung the game decisively Yorkshire's way with two wickets in four balls. Chris Taylor got a top edge for Brophy to pull off a well-judged catch and Stephen Snell had his leg stump ripped clean out of the ground.

Gloucestershire stayed in the hunt while Marshall was still there but, the ball after driving Bresnan to the extra cover boundary to go to his 50 off 55 balls, he was bowled making too much room. Ed Young could not beat Pyrah's throw to the wicketkeeper and with wickets tumbling, the same fielder finished things off by running out last man Anthony Ireland.

After winning the toss, Yorkshire got off to a dashing start but were then pegged back for a while by two of their former players in off-spinner Richard Dawson and paceman Steve Kirby.

Dawson bowled Jacques Rudolph with the final delivery of his first over to end an opening stand of 71 in 12 overs with skipper Andrew Gale, who was then run out for a breezy 61 when Kirby scored a direct hit on the stumps from short third man.

Dawson also got rid of the potentially dangerous Adam Lyth for seven to leave Yorkshire on 119 for three and they were able to recover their momentum through a chanceless 76 from McGrath.

Gale dominated his first-wicket partnership with Rudolph and he drove Jon Lewis high over long-off for six before thumping a free hit back past Kirby for another boundary.

Rudolph, who went into the match averaging over 100 in the competition, hit two exquisite boundaries through cover off Lewis, but it was Gale who accelerated the scoring by taking two fours and a six off consecutive balls when Ireland joined the attack.

Soon after Rudolph's departure, Gale completed a robust half-century from 46 deliveries with five fours and two sixes but, with the total on 103 in the 18th over, McGrath played Dawson to short third man and set off for a single, Gale being short of his crease when Kirby shied into the stumps.

Left-armer Young, in only his second match for Gloucestershire, kept Yorkshire in check with Dawson who then dismissed Lyth lbw to finish with two for 32, Young's eight overs costing 33.

McGrath moved cautiously towards his 50, which he reached with his third four, and he and Brophy were able to boost the scoring rate once the pace bowlers returned, both batsmen profiting from an untidy over from Lewis which leaked 23 runs.

The fourth-wicket pair had added 75 together when Brophy fell to Kirby for 33 and the bowler struck again by having McGrath caught in the deep after receiving 80 balls and striking seven boundaries. Jonny Bairstow and Bresnan ensured the innings ended with a flourish, 86 coming off the last seven overs.